Scientific Papers in SCI
2023
2023
Materiales Ópticos Multifuncionales
Collective plasmonic resonances enhance the photoluminescence of rare-earth nanocrystal films processed by ultrafast annealing
Cabello-Olmo, E; Higashino, M; Murai, S; Tanaka, K; Lozano, G; Miguez, HChemical Communications, 59 (2023) 1289-1292 DOI: 10.1039/d2cc04779a

Abstract
Herein, we demonstrate that rapid thermal annealing allows achieving close-to-one photoluminescence quantum yield while preserving the transparency of rare-earth nanocrystal films, which further enables their integration with nanophotonics. The combination with periodic arrays of aluminum nanodisks that support collective plasmonic resonances leads to enhanced directional emission.
January, 2023 · DOI: 10.1039/d2cc04779a
Química de Superficies y Catálisis
Highly dispersed Rh single atoms over graphitic carbon nitride as a robust catalyst for the hydroformylation reaction
Jurado, L; Esvan, J; Luque-Alvarez, LA; Bobadilla, LF; Odriozola, JA; Posada-Perez, S; Poater, A; Comas-Vives, A; Axet, MRCatalysis Science & Tecnology, 13 (2022) 1425-1436 DOI: 10.1039/d2cy02094g

Abstract
Rhodium-catalysed hydroformylation, effective tool in bulk and fine-chemical synthesis, predominantly uses soluble metal complexes. For that reason, the metal leaching and the catalyst recycling are still the major drawbacks of this process. Single-atom catalysts have emerged as a powerful tool to combine the advantages of both homogeneous and heterogeneous catalysts. Since using an appropriate support material is key to create stable, finely dispersed, single-atom catalysts, here we show that Rh atoms anchored on graphitic carbon nitride are robust catalysts for the hydroformylation reaction of styrene.
January, 2023 · DOI: 10.1039/d2cy02094g
Materiales Ópticos Multifuncionales
Responsive Optical Materials Based on Ligand-Free Perovskite Quantum Dots Embedded in Mesoporous Scaffolds
Romero-Perez, C; Zanetta, A; Fernandez-Delgado, N; Herrera-Collado, M; Hernandez-Saz, J; Molina, SI; Calio, L; Calvo, ME; Miguez, HACS Applied Materials & Interfaces 15 (2023) 1808-1816 DOI: 10.1021/acsami.2c16867

Abstract
Herein we show that dispersing inorganic cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) in optical quality films, possessing an accessible and controlled pore size distribution, gives rise to fluorescent materials with a controlled and highly sensi t i v e response to ambient changes. A scaffold-based synthesis approach is employed to obtain ligand-free QDs, whose pristine surface endows them with high sensit i v i t y to the presence of different vapors in their vici n i t y . At the same time, the void network of the host offers a means to gradually expose the embedded QDs to such vapors. Under these conditions, the luminescent response of the QDs is mediated by the mesostructure of the matri x , which determines the rate at which vapor molecules will adsorb onto the pore walls and, eventually, condensate, filling the void space. With luminescence quantum yields as high as 60%, scaffold-supported ligand-free perovskite nanocrystals display intense photoemission signals over the whole process, as well as high photo-and chemical stabi l i t y , which allows illuminating them for long periods of time and recovering the original response upon desorption of the condensed phase. The results herein presented open a new route to explore the application of perovskite QD-based materials in sensing.
January, 2023 · DOI: 10.1021/acsami.2c16867
Reactividad de Sólidos
A novel, green, cost-effective and fluidizable SiO2-decorated calcium-based adsorbent recovered from eggshell waste for the CO2 capture process
Imani, M; Tahmasebpoor, M; Sanchez-Jim, P; Valverde, J; Garcia, VMSeparation and Purification Technology, 305 (2023) 122523 DOI: 10.1016/j.seppur.2022.122523

Abstract
The reduction, storage, and reuse of greenhouse gas carbon dioxide (CO2) is a crucial concern in modern society. Bio-waste adsorbents have recently aroused the investigator's attention as auspicious materials for CO2 capture. However, the adsorption capacity decaying and poor fluidizability during carbonation/calcination cycles of all natural adsorbents used in the calcium-looping process (CaL) are important challenges. The current study ex-plores the performance of a novel SiO2-decorated calcium-based adsorbent recovered from eggshell waste in terms of both CO2 capture capacity and fluidity. Two preparation methods of hydration and sol-gel were used to obtain Ca-based adsorbents with different pore configurations and volumes. Modification of the adsorbents was applied by dry physically mixing with different weight percentages of hydrophobic SiO2 nanoparticles (NPs), in order to maintain stability and fluidity. The adsorbent prepared by the sol-gel method exhibited a fluffier structure with smaller grain sizes and higher porosity than that of prepared by the hydration method, leading to a 6.9 % increase in conversion at the end of the 20th cycle. Also, with the optimal amount of SiO2 nanoparticles, i. e. 7.5 wt%, the amount of CaO conversion obtained by sol-gel derived adsorbent was 27.59 % higher than that by pristine eggshell at the end of the 20th carbonation/calcination cycles. The fluidizability tests showed that the highest bed expansion ratio (2.29) was achieved for sol-gel derived adsorbent in the presence of 7.5 wt% silica nanoparticles which was considerably higher than the amount of 1.8 and 1.6 belonged to sol-gel derived adsorbent and pristine eggshell without silica at the gas velocity of approximate to 6.5 cm/s, respectively. The high adsorption capacity and proper fluidity of this novel and green calcium-based adsorbent promise its wide application.
January, 2023 · DOI: 10.1016/j.seppur.2022.122523
Materiales Avanzados
Sintering behaviour of a clay containing pyrophyllite, sericite and kaolinite as ceramic raw materials: Looking for the optimum firing conditions
Sanchez-Soto, PJ; Garzon, E; Perez-Villarejo, L; Eliche-Quesada, DBoletin de la Sociedad Española de Ceramica y Vidrio, 62 (2023) 26-39 DOI: 10.1016/j.bsecv.2021.09.001
Abstract
The sintering behaviour of a pyrophyllite clay has been investigated. The mineralogical composition by X-ray diffraction (XRD) of this sample was -35 wt.% pyrophyllite, -25 wt.% sericite/illite, -15 wt.% kaolinite and -20 wt.% quartz. The chemical composition was consistent with these results, with a total flux content of 4.18 wt.%. Prismatic bars were prepared by dry pressing using this sample and fired in the range 800-1500 degrees C with 0.5-5 h of soaking times. Sintering diagrams were obtained using the results of linear firing shrinkage, water absorption capacity, bulk density and apparent porosity determined in the ceramic bodies as a function of firing temperatures. It was found a trend of slight variations of bulk density values firing in the range 1000-1150 degrees C, with marked decreases of these values for these bodies fired at 1200 degrees C and 1300 degrees C. The temperature of maximum bulk density was determined as -1200 degrees C and the vitrification temperature was -1300 degrees C where the apparent porosity becomes almost zero. The vitrification process of the pyrophyllite clay sample was investigated using a method previously described in the literature, which considered an Arrhenius approach under isothermal conditions and a first order kinetic. It was determined an activation energy (Ea) of -45 kJ/mol with a linear correlation coefficient of 0.998. The relative rates of vitrification were calculated. It was found that the contribution of vitrification due to the heating was relatively small compared to the vitrification during soaking. Mullite and quartz are forming the ceramic bodies besides a vitreous or glassy phase. The thermally treated pyrophyllite clay showed a dense network of rod-shaped and elongated needle-like crystals, being characteristic features of mullite as a dense felt. The vitrification rate equation, as deduced in this study by first time, can be a useful tool to estimate the optimum firing conditions of the pyrophyllite clays applied as ceramic raw materials.
January, 2023 · DOI: 10.1016/j.bsecv.2021.09.001
Química de Superficies y Catálisis
Engineering morphologies of yttrium oxide supported nickel catalysts for hydrogen production
Zhang, RB; Tu, ZA; Meng, S; Feng, G; Lu, ZH; Yu, YZ; Reina, TR; Hu, FY; Chen, XH; Ye, RPRare Metals, 42 (2023) 176-188 DOI: 10.1007/s12598-022-02136-5
Abstract
The catalytic performance is highly related to the catalyst structure. Herein, a series of Ni nanoparticles supported on Y2O3 with different morphologies were successfully synthesized via hydrothermal process screening different pH environments. These Ni/Y2O3 catalysts were applied to efficiently produce COx-free H-2 through ammonia decomposition. We identify a significant impact of Y2O3 supports on nickel nanoclusters sizes and dispersion. The experimental results show that Ni/Y11 catalyst achieves 100% ammonia decomposition conversion under a gas hour space velocity (GHSV) of 12,000 ml.h(-1).g(cat)(-1) and temperature of 650 degrees C. Such a high level of activity over Ni/Y11 catalyst was attributed to a large specific surface area, appropriate alkalinity, and small Ni nanoparticles diameter with high dispersion.
January, 2023 · DOI: 10.1007/s12598-022-02136-5
Reactividad de Sólidos
Thermal arrest analysis of the reverse martensitic transformation in a Ni55Fe19Ga26 Heusler alloy obtained by melt-spinning
Vidal-Crespo, A; Manchon-Gordon, AF; Blazquez, JS; Ipus, JJ; Svec, P; Conde, CFJournal of Thermal Analysis and Calorimetry, (2023) DOI: 10.1007/s10973-022-11889-1
Abstract
Ni55Fe19Ga26 ribbons obtained by melt-spinning technique exhibit a martensitic transformation from L2(1) cubic austenite phase to 14 M martensite phase above room temperature. We have taken advantage of the existence of thermal hysteresis of the martensitic phase transition (similar to 11 K) to analyze the effect of isothermal treatments on the reverse martensitic transformation, which has been analyzed by means of interrupted heating using differential scanning calorimetry. The experimental findings clearly indicate a time-depending effect in the martensitic transformation at temperatures between the austenite start and finish temperatures. Moreover, it has been observed that two successive martensitic transformations take place after the isothermal arrest was performed.
January, 2023 · DOI: 10.1007/s10973-022-11889-1
Nanotecnología en Superficies y Plasma
Determination of the Primary Excitation Spectra in XPS and AES
Pauly, N; Yubero, F; Tougaard, SNanomaterials, 13 (2023) 339 DOI: 10.3390/nano13020339

Abstract
This paper reviews a procedure that allows for extracting primary photoelectron or Auger electron emissions from homogeneous isotropic samples. It is based on a quantitative dielectric description of the energy losses of swift electrons travelling nearby surfaces in presence of stationary positive charges. The theory behind the modeling of the electron energy losses, implemented in a freely available QUEELS-XPS software package, takes into account intrinsic and extrinsic effects affecting the electron transport. The procedure allows for interpretation of shake-up and multiplet structures on a quantitative basis. We outline the basic theory behind it and illustrate its capabilities with several case examples. Thus, we report on the angular dependence of the intrinsic and extrinsic Al 2s photoelectron emission from aluminum, the shake-up structure of the Ag 3d, Cu 2p, and Ce 3d photoelectron emission from silver, CuO and CeO2, respectively, and the quantification of the two-hole final states contributing to the L3M45M45 Auger electron emission of copper. These examples illustrate the procedure, that can be applied to any homogeneous isotropic material.
January, 2023 · DOI: 10.3390/nano13020339
Química de Superficies y Catálisis
Is the RWGS a viable route for CO2 conversion to added value products? A techno-economic study to understand the optimal RWGS conditions
Portillo, E; Gandara-Loe, J; Reina, TR; Pastor-Perez, LScience of the Total Environment, 857 (2023) 159394 DOI: 10.1016/j.scitotenv.2022.159394

Abstract
Understanding the viability of the RWGS from a thermodynamic and techno-economic angle opens new horizons within CO2 conversion technologies. Unfortunately, profitability studies of this technology are scarce in literature and mainly focused on overall conversion and selectivity trends with tangential remarks on energy demands and pro-cess costs. To address this research gap, herein we present a comprehensive techno-economic study of the RWGS reac-tion when coupling with Fischer-Tropsch synthesis is envisaged to produced fuels and chemicals using CO2 as building block. We showcase a remarkable impact of operating conditions in the final syngas product and both CAPEX and OPEX. From a capital investment perspective, optimal situations involve RWGS unit running at low temperatures and high pressures as evidenced by our results. However, from the running cost angle, operating at 4 bar is the most favorable alternative within the studied scenarios. Our findings showcase that, no matter the selected temperature the RWGS unit should be preferentially run at intermediate pressures. Ultimately, our work maps out multiple operat-ing scenarios in terms of energy demand and process cost serving as guideline to set optimal reaction conditions to un-lock the potential of the RWGS for chemical CO2 recycling.
January, 2023 · DOI: 10.1016/j.scitotenv.2022.159394
Reactividad de Sólidos
Low Temperature Magnetic Transition of BiFeO3 Ceramics Sintered by Electric Field-Assisted Methods: Flash and Spark Plasma Sintering
Manchon-Gordon, AF; Perejon, A; Gil-Gonzalez, E; Kowalczyk, M; Sanchez-Jimenez, PE; Perez-Maqueda, LAMaterials, 16 (2023) 189 DOI: 10.3390/ma16010189
Abstract
Low temperature magnetic properties of BiFeO3 powders sintered by flash and spark plasma sintering were studied. An anomaly observed in the magnetic measurements at 250 K proves the clear existence of a phase transition. This transformation, which becomes less well-defined as the grain sizes are reduced to nanometer scale, was described with regard to a magneto-elastic coupling. Furthermore, the samples exhibited enhanced ferromagnetic properties as compared with those of a pellet prepared by the conventional solid-state technique, with both a higher coercivity field and remnant magnetization, reaching a maximum value of 1.17 kOe and 8.5 10(-3) emu/g, respectively, for the specimen sintered by flash sintering, which possesses the smallest grains. The specimens also show more significant exchange bias, from 22 to 177 Oe for the specimen prepared by the solid-state method and flash sintering technique, respectively. The observed increase in this parameter is explained in terms of a stronger exchange interaction between ferromagnetic and antiferromagnetic grains in the case of the pellet sintered by flash sintering.
January, 2023 · DOI: 10.3390/ma16010189
Nanotecnología en Superficies y Plasma
A Holistic Solution to Icing by Acoustic Waves: De-Icing, Active Anti-Icing, Sensing with Piezoelectric Crystals, and Synergy with Thin Film Passive Anti-Icing Solutions
Del Moral, J; Montes, L; Rico-Gavira, VJ; Lopez-Santos, C; Jacob, S; Oliva-Ramirez, M; Gil-Rostra, J; Fakhfouri, A; Pandey, S; Del Val, MG; Mora, J; García-Gallego, P; Ibanez-Ibanez, PF; Rodríguez Valverde, MA; Winkler, A; Borras, A; Gonzalez-Elipe, ARAdvanced Functional Materials, 33 (2023) 2209421 DOI: 10.1002/adfm.202209421
Abstract
Icing has become a hot topic both in academia and in the industry given its implications in transport, wind turbines, photovoltaics, and telecommunications. Recently proposed de-icing solutions involving the propagation of acoustic waves (AWs) at suitable substrates may open the path for a sustainable alternative to standard de-icing or anti-icing procedures. Herein, the fundamental interactions are unraveled that contribute to the de-icing and/or hinder the icing on AW-activated substrates. The response toward icing of a reliable model system consisting of a piezoelectric plate activated by extended electrodes is characterized at a laboratory scale and in an icing wind tunnel under realistic conditions. Experiments show that surface modification with anti-icing functionalities provides a synergistic response when activated with AWs. A thoughtful analysis of the resonance frequency dependence on experimental variables such as temperature, ice formation, or wind velocity demonstrates the application of AW devices for real-time monitoring of icing processes.
January, 2023 · DOI: 10.1002/adfm.202209421
2022
2022
Química de Superficies y Catálisis
Materials challenges and opportunities to address growing micro/ nanoplastics pollution: a review of thermochemical upcycling
Parrilla-Lahoz, S; Mahebadevan, S; Kauta, M; Zambrano, MC; Pawlak, JJ; Venditti, RA; Reina, TR; Duyar, MSMaterials Today Sustainability, 20 (2022) 100200 DOI: 10.1016/j.mtsust.2022.100200

Abstract
Micro/nanoplastics have sparked attention in recent years due to their widespread presence in the environment. Currently, several waste valorization approaches are under development in order to upcycle micro/nanoplastics. Thermal conversion technologies such as pyrolysis, gasification, liquefaction, or hydrothermal carbonization can yield high-value solid products, oil, and gases from plastics waste. The common thermal conversion technologies investigated focus on maximizing the production of oil and gases (such as H2 and CH4) for use as fuel. Except for hydrogen, when these products are used to generate energy, the carbon emissions generated are comparable to those produced by traditional fossil fuels. Herein, we present a review of the current efforts to capture and convert plastic waste into valuable products with an emphasis on identifying the need to develop processes specifically for micro/nano-plastics while also preventing the release of CO2 emissions. We identify the development of efficient catalytic materials as a critical research need for achieving economically viable thermochemical con-version of micro/nanoplastics.
December, 2022 · DOI: 10.1016/j.mtsust.2022.100200
Química de Superficies y Catálisis
Development of Power-to-X Catalytic Processes for CO2 Valorisation: From the Molecular Level to the Reactor Architecture
Bobadilla, LF; Azancot, L; Luque-Alvarez, LA; Torres-Sempere, G; Gonzalez-Castano, M; Pastor-Perez, L; Ramírez-Reina, T; Ivanova, S; Centeno, MA; Odriozola, JAChemistry, 4 (2022) 1250-1280 DOI: 10.3390/chemistry4040083
Abstract
Nowadays, global climate change is likely the most compelling problem mankind is facing. In this scenario, decarbonisation of the chemical industry is one of the global challenges that the scientific community needs to address in the immediate future. Catalysis and catalytic processes are called to play a decisive role in the transition to a more sustainable and low-carbon future. This critical review analyses the unique advantages of structured reactors (isothermicity, a wide range of residence times availability, complex geometries) with the multifunctional design of efficient catalysts to synthesise chemicals using CO2 and renewable H-2 in a Power-to-X (PTX) strategy. Fine-chemistry synthetic methods and advanced in situ/operando techniques are essential to elucidate the changes of the catalysts during the studied reaction, thus gathering fundamental information about the active species and reaction mechanisms. Such information becomes crucial to refine the catalyst's formulation and boost the reaction's performance. On the other hand, reactors architecture allows flow pattern and temperature control, the management of strong thermal effects and the incorporation of specifically designed materials as catalytically active phases are expected to significantly contribute to the advance in the valorisation of CO2 in the form of high added-value products. From a general perspective, this paper aims to update the state of the art in Carbon Capture and Utilisation (CCU) and PTX concepts with emphasis on processes involving the transformation of CO2 into targeted fuels and platform chemicals, combining innovation from the point of view of both structured reactor design and multifunctional catalysts development.
December, 2022 · DOI: 10.3390/chemistry4040083
Química de Superficies y Catálisis
CO2 methanation on Ni/YMn1-xAlxO3 perovskite catalysts
Safdar, M; Gonzalez-Castano, M; Penkova, A; Centeno, MA; Odriozola, JA; Arellano-Garcia, HApplied Materials Today, 29 (2022) 101577 DOI: 10.1016/j.apmt.2022.101577

Abstract
Seeking for advanced catalytic systems for the CO2 methanation reaction, the use of Ni supported catalysts over redox materials is often proposed. Profiting the superior redox properties described for layered perovskite systems, this work has investigated a series Ni supported YMn1-xAlxO3 (x = 0, 0.2, 0.5, 0.8, 1) perovskite catalysts. The obtained results evidenced the impact of the support nature on the systems redox properties and Ni-support interactions. Within the catalysts series, the greater methanation rates displayed by Ni/YMn0.5Al0.5O3 catalyst (0.748 mmol(CO2,conv.)s(-1) g(Ni)(-1) at 400 ? and 60 L/gh) were associated to the interplay between the support redox properties and superior Ni dispersion. The improved redox behavior attained through the Al-incorporation (up to x = 0.5) was associated to the layered perovskite structures which, being distorted and constituted by smaller crystal sizes, facilitated the behavior of Mn redox couples as surface species readily interconverted. Exhibiting catalytic performances comparable to precious metals based catalysts, this work proposes the Ni/YMn0.5Al0.5O3 catalyst as an effective system for the CO2 methanation reaction.
December, 2022 · DOI: 10.1016/j.apmt.2022.101577
Tribología y Protección de Superficies
High-Quality SiO2/O-Terminated Diamond Interface: Band-Gap, Band-Offset and Interfacial Chemistry
Canas, J; Reyes, DF; Zakhtser, A; Dussarrat, C; Teramoto, T; Gutierrez, M; Gheeraert, ENanomaterials, 12 (2022) 4125 DOI: 10.3390/nano12234125
Abstract
Silicon oxide atomic layer deposition synthesis development over the last few years has open the route to its use as a dielectric within diamond electronics. Its great band-gap makes it a promising material for the fabrication of diamond-metal-oxide field effects transistor gates. Having a sufficiently high barrier both for holes and electrons is mandatory to work in accumulation and inversion regimes without leakage currents, and no other oxide can fulfil this requisite due to the wide diamond band-gap. In this work, the heterojunction of atomic-layer-deposited silicon oxide and (100)-oriented p-type oxygen-terminated diamond is studied using scanning transmission electron microscopy in its energy loss spectroscopy mode and X-ray photoelectron spectroscopy. The amorphous phase of silicon oxide was successfully synthesized with a homogeneous band-gap of 9.4 eV. The interface between the oxide and diamond consisted mainly of single- and double-carbon-oxygen bonds with a low density of interface states and a straddling band setting with a 2.0 eV valence band-offset and 1.9 eV conduction band-offset.
December, 2022 · DOI: 10.3390/nano12234125
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Assessment of pilot-plant scale solar photocatalytic hydrogen generation with multiple approaches: Valorization, water decontamination and disinfection
Ruiz-Aguirre, A; Villachica-Llamosas, JG; Polo-Lopez, MI; Cabrera-Reina, A; Colon, G; Peral, J; Malato, SEnergy, 260 (2022) e10272 DOI: 10.1016/j.energy.2022.125199
Abstract
The main goal of the present study was to explore pilot-scale combination of H-2 generation with simultaneous water disinfection or decontamination. Performance of a TiO2-CuO mixture for solar-to-hydrogen (STH) con-version was studied, focusing on treatment optimization (catalyst dose, proportion of semiconductors in the mixture and concentration of the sacrificial agent). Experiments were performed in a 25-L compound parabolic collector (2 m(2)) solar pilot plant specifically designed for photocatalytic hydrogen generation. The best operating conditions were 100 mg L-1 TiO2-CuO (10:1) with 0.075 M glycerol as the sacrificial agent. The best STH conversion attained was 0.9%. 25 mg L-1 imidacloprid was completely degraded (over 99%). The synergetic effect of anoxic conditions, TiO2:CuO and solar radiation caused a significant reduction (> 5 Log) in concen-tration of E. coli, used as a model waterborne pathogen, in less than 10 min.
December, 2022 · DOI: 10.1016/j.energy.2022.125199
Materiales Nanoestructurados y Microestructura
Pd supported on defective TiO2 polymorphic mixtures: Effect of metal-support interactions upon glycerol selective oxidation
Rinaudo, MG; Beltran, AM; Fernandez, A; Cadus, LE; Morales, MRResults in Engineering, 16 (2022) 100737 DOI: 10.1016/j.rineng.2022.100737

Abstract
Palladium catalysts supported on defective mixes of anatase, TiO2 (II) and rutile crystalline phases, previously obtained by high-energy ball milling, were synthesized and tested for glycerol selective oxidation. A deep characterization of these unusual materials was carried out to elucidate catalytic and physicochemical features. Electron density transfer from support to metal or vice versa, depending on the polymorphs present, could not only alter palladium particle sizes and its surface oxidation state but also reducibility and oxygen mobility of catalysts. Furthermore, acid-base properties achieved also influenced catalytic activity under mild conditions of liquid-phase glycerol oxidation. A conversion of 94% and a selectivity to glyceric and lactic acids of 48% and 22% respectively were obtained for the Pd catalyst supported on mechanochemically activated anatase. The presence of several polymorphs in a metal oxide support could therefore benefit or handicap catalytic cycle for a particular reaction. Metal-support interactions play a key role in heterogenous catalysts and thus the rational design of supports comes on the scene.
December, 2022 · DOI: 10.1016/j.rineng.2022.100737
Reactividad de Sólidos
Theoretical Analysis of Polynuclear Zinc Complexes Isolobally Related to Hydrocarbons
Ayala, R; Galindo, AInternational Journal of Molecular Sciences, 23 (2022) 14858 DOI: 10.3390/ijms232314858
Abstract
Based on the isolobal analogy of ZnCp (Cp = eta(5)-C5H5) and ZnR (R = alkyl or aryl group) fragments with hydrogen atom and fragment [Zn(CO)(2)] with a CH2 carbene, the following complexes [(ZnCp)(2){mu-Zn(CO)(2)}], 1, [(ZnPh)(2){mu-Zn(CO)(2)}], 2, [(ZnPh){mu-Zn(CO)(2)}(ZnCp)], 3, [(ZnCp)(2){mu-Zn-2(CO)(4)}], 4, [(ZnPh)(2){mu-Zn-2(CO)(4)}], 5, [(ZnPh){mu-Zn(CO)(2)}(2)(ZnCp)], 6, [Zn-3(CO)(6)], 7 and [Zn-5(CO)(10)], 8, were built. These polynuclear zinc compounds are isolobally related to simple hydrocarbons (methane, ethane, cyclopropane and cyclopentane). They have been studied by density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) to compare the nature and topology of the Zn-Zn bond with previous studies. There are bond critical points (BCPs) between each pair of adjacent Zn centers in complexes 1-8 with Zn-Zn distances within the range 2.37-2.50 angstrom. The nature of the Zn-Zn bond in these complexes can be described as polar rather than pure covalent bonds. Although in a subtle way, the presence of different ligands and zinc oxidation states introduces asymmetry and polarity in the Zn-Zn bond. In addition, the Zn-Zn bond is delocalized in nature in complex 7 whereas it can be described as a localized bond for the remaining zinc complexes here studied.
December, 2022 · DOI: 10.3390/ijms232314858
Reactividad de Sólidos
Improvement in cyclic CO2 capture performance and fluidization behavior of eggshell-derived CaCO3 particles modified with acetic acid used in calcium looping process
Imani, M; Tahmasebpoor, M; Sanchez-Jimenez, PE; Valverde, JM; Moreno, VJournal of CO2 Utilization, 65 (2022) 102207 DOI: 10.1016/j.jcou.2022.102207

Abstract
Although calcium-based materials are the most promising adsorbents used in calcium looping process for carbon dioxide removing, their CO2 capture capacity decaying besides poor fluidization, still are the important challenges. In the present investigation, eggshell as a cheap, easily available and unpolluted source of calcium carbonate was used for CO2 capturing in calcium looping process. Eggshell particles were treated with various volume concentrations of acetic acid to improve its sorption capacity. According to the TGA results after 20 carbonation/calcination cycles, the effective carbonation conversion of modified eggshell with 5%, 20%, 30% and 40%. v/v acetic acid was 21.33%, 24.26%, 25.97% and 28.97%, respectively, which is considerable compared to 20.54% for untreated eggshell. The effect of initial eggshell particle size on the adsorption behavior of final adsorbent was also investigated by using two different sizes including dp < 45 mu m and dp > 320 mu m. The results showed that the effective conversion of the adsorbent containing 40%. v/v acetic acid derived from small particle size eggshells was 9.32% higher than that from larger particle size eggshells. In terms of fluidization behavior, surprisingly the addition of acetic acid to the eggshell particles also increased the bed expansion ratio as 8% and 36.2% at gas velocities of 0.27 and 6.67 cm/s, respectively. Further improvement in the fluidity of eggshell modified with 40% acid was performed by manually mixing of SiO2 nanoparticles at different weight percentages. According to the results, adding 7.5 wt% SiO2 leaded to the homogeneous and agglomerate particulate fluidization.
November, 2022 · DOI: 10.1016/j.jcou.2022.102207
Materiales de Diseño para la Energía y Medioambiente
Biopolymer-Based Films Reinforced with FexOy-Nanoparticles
Abdullah, JAA; Jimenez-Rosado, M; Benitez, JJ; Guerrero, A; Romero, APolymers, 14 (2022) 4487 DOI: 10.3390/polym14214487
Abstract
Nowadays, natural polymer-based films are considered potentially environmentally friendly alternatives to conventional plastic films, due to many advantageous properties, including their easy processability, high flexibility, non-toxicity, low cost, high availability, and environmental safety. However, they are limited in their application by a number of shortcomings, including their high water solubility and vapor permeability as well as their poor opacity and low mechanical resistance. Thus, nanoparticles, such as green FexOy-NPs, can be used to overcome the drawbacks associated with these materials. Therefore, the aim of this study was to develop three different polymer-based films (gelatin-based, cellulose acetate-based and chitosan-based films) containing green synthesized FexOy-NPs (1.0% w/w of the initial polymer weight) as an additive to improve film properties. This was accomplished by preparing the different films using the casting method and examining their physicochemical, mechanical, microstructural, and functional characteristics. The results show that the incorporation of FexOy-NPs into the different films significantly enhanced their physicochemical, mechanical, and morphological properties as well as their antioxidant characteristics. Consequently, it was possible to produce suitable natural polymer-based films with potential applications across a wide range of industries, including functional packaging for food, antioxidants, and antimicrobial additives for pharmaceutical and biomedical materials as well as pesticides for agriculture.
November, 2022 · DOI: 10.3390/polym14214487
Materiales de Diseño para la Energía y Medioambiente
Transparency of polymeric food packaging materials
Guzman-Puyol, Susana; Benitez, Jose J; Heredia-Guerrero, Jose AFood Research International, 161 (2022) 111792 DOI: 10.1016/j.foodres.2022.111792

Abstract
Transparency is a very important technical parameter to evaluate and validate certain food packaging materials. In the recent scientific literature, several methods (i.e. transmittance, opacity, haze, and absorbance) have been used and such variety hinders a direct comparison of results from different authors. In this Review, we describe and discuss the most widely employed methods to measure transparency, with special emphasis on two main parameters: transmittance and opacity. Moreover, a comparison of the different techniques is addressed and the typical values of transmittance and opacity of common transparent food packaging materials are provided. Our current opinion is that transparency should be expressed as transmittance in the visible range due to both the quickness and easiness of the measurement and the standardization of data. This information should be accompanied by the thickness value and a graphical image of the analysed samples for a useful and complete characterization.
November, 2022 · DOI: 10.1016/j.foodres.2022.111792
Monitoring the Simultaneous Implantation of Ti and Tb Cations to a Sacrificial Template and the Sol-Gel Synthesis of Tb-Doped TiO2 (Anatase) Hollow Spheres and Their Transition to Rutile Phase
Colomer, MT; Vattier, FInternational Journal of Molecular Sciences, 23 (2022) 13162 DOI: 10.3390/ijms232113162
Abstract
Tb-doped TiO2 (anatase) micro-hollow spheres (HSs) with nano-shells, in the range 0.00-3.00 at.% Tb, were successfully synthesized by a simultaneous chemical implantation route of both Ti and Tb cations from chlorides to a poly-styrene (PST)-co-poly-divinyl benzene (PDVB) sacrificial template, followed by controlled hydrolysis and polycondensation reactions. After water addition to the mixture of the precursors with the template, a decrease in the intensity and a shift to lower wavenumbers of the C=O absorption band in the IR spectra can indicate not only the anchoring of Ti and Tb ions to the carbonyl group of the template but also the hydrolysis of the implanted precursors. This latter process can involve a proton attack on the Ti-Cl, Tb-Cl and C=O bonds, the occupation of a vacant site by a water molecule, and then the dissociation of the dangling Ti-Cl, Tb-Cl ligands and C=O bonds. It gives rise to Ti1-xTbx[(OH)(4-u)Cl-v]@PST-PDVB and Ti1-xTbx[(OH)(4-y)]@PST-PDVB complexes (x = 0.00, 0.0012, 0.0170 and 0.030). Finally, polycondensation of these species leads to Ti1-xTbxO2-w'@PST-PDVB compounds. After subsequent thermal removal at 550 degrees C of the template, the IR bands of the core (template) totally vanished and new bands were observed in the 400-900 cm(-1) region which can be attributed to the metalloxane bondings (M-O, M'-O, M-O-M, M-O-M' and/or M'-O-M', being M and M' = Ti and Tb, respectively, i.e., mainly vibration modes of anatase). Then, micron-sized HSs of TiO2 and Tb-doped-TiO2 (anatase) were obtained with nano-shells according to field emission gun scanning electron microscopy (FEG-SEM) and transmission electron microscopy (TEM) observations. Furthermore, X-ray photoelectron spectroscopy (XPS) measurements confirmed the presence of Tb4+ (38.5 and 41.2% for 1.70 and 3.00 at.% Tb, respectively) in addition to Tb3+ in the resulting HSs, with increasing Tb4+ content with both Tb doping and higher calcination temperatures. Then, these HSs can be considered as rare earth (RE) co-doped systems, at least for 1.70 and 3.00 at.% Tb contents being the transition to rutile phase favored by Tb doping for those compositions. Finally, diffusion of Tb from the inner parts to the surface of the HSs with the calcination treatments was also observed by XPS.
November, 2022 · DOI: 10.3390/ijms232113162
Fotocatálisis Heterogénea: Aplicaciones
Effective photocatalytic conversion of formic acid using iron, copper and sulphate doped TiO2
Zouheir, M; Tanji, K; Navío, JA; Hidalgo, MC; Jaramillo-Paez, CA; Kherbeche, AJournal of Central South University, 29 (2022) 3592-3607 DOI: 10.1007/s11771-022-5172-9
Abstract
In this paper, the combined addition of copper or iron and sulphate ions onto TiO2 prepared by a simple sol-gel method is studied for formic acid photocatalytic conversion. A wide structural and morphological characterization of the different photocatalysts was performed by X-ray diffraction (XRD), N2-physisorption for BET surface area measurements, scanning and transmission electronic microscopies (SEM and TEM), UV-Vis diffuse spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS), in order to correlate the physico-chemical properties of the materials to their photocatalytic efficiencies for formic acid oxidation. Results have shown important differences among the catalysts depending on the metal added. Sulphated TiO2/Cu (1%Cu) was the best photocatalyst obtaining about 100% formic acid conversion in only 5 min. The appropriate physico-chemical features of this photocatalyst, given by the addition of combined copper and sulphate ions, explain its excellence in photocatalytic reaction.
November, 2022 · DOI: 10.1007/s11771-022-5172-9
Materiales Nanoestructurados y Microestructura
Morphologically diverse CaCO3 microparticles and their incorporation into recycled cellulose for circular economy
Guerra-Garces, J; Garcia-Negrete, CA; Pastor-Sierra, K; Arteaga, GC; Barrera-Vargas, M; de Haro, MJ; Fernandez, AMaterials Today Sustainability, 19 (2022) 100166 DOI: 10.1016/j.mtsust.2022.100166
Abstract
The main raw material for manufacture of paper is cellulose fibers that can be virgin or recycled. Globally, 70% of the Tetra Pak packages sold are not recycled and remain as unused wastes. Therefore, the development of alternatives to promote greater recycling and sustainable use of these packages is of great interest. In this study, the formation of precipitated calcium carbonates (PCC) in the presence of carboxymethyl cellulose (CMC) is studied at different temperatures, and the morphologically diverse particles obtained are explored as filler for composites based on cellulosic fibers recovered from Tetra Pak containers. It was found that the addition of filler does not lead to deterioration of either tensile strength or thermal and stability of the obtained composite samples. Results also suggest that the morphological diversity of the filler contributes to a more efficient filling of the interfibrillar spaces of cellulosic fibers and, in turn, to the fiber and filler compatibility.
November, 2022 · DOI: 10.1016/j.mtsust.2022.100166
Reactividad de Sólidos
Supercooled sodium acetate aqueous solution for long-term heat storage to support heating decarbonisation
Lizana, J; Sanchez-Jimenez, PE; Chacartegui, R; Becerra, JA; Perez-Maqueda, LAJournal of Energy Storage, 55 (2022) 105584 DOI: 10.1016/j.est.2022.105584
Abstract
Heating decarbonisation through electrification requires the development of novel heat batteries. They should be suitable for the specific application and match the operation conditions of domestic renewable energy sources. Supercooled liquids, often considered a drawback of phase change materials, are among the most promising technologies supporting heating decarbonisation. Although some studies have shed light on stable supercooling, the fundamentals and stability remain open problems not always accompanied by relevant experimental in-vestigations. This research critically analyses the physic and chemistry of sodium acetate (SA, NaCH3COO) aqueous solution, a low-cost, non-toxic, and abundant compound with stable supercooling for long-term heat storage. It has an appropriate phase change temperature for high-density heat storage using heat pumps or solar thermal technologies in residential applications. The existing discrepancies in literature are critically discussed through a systematic experimental evaluation, providing novel insights into efficient material design and appropriate boundary conditions for reliable material use in long-term heat batteries. Despite previous studies showing that the thermal reliability and stability of sodium acetate aqueous solution as a supercooled liquid for heat storage cannot be guaranteed, this study demonstrates that through an appropriate encapsulation and sealing method, the peritectic composition of sodium acetate solution (p-SA 58 wt%) can be used as a super-cooled liquid for long-term heat storage with a stable melting temperature of 57 degrees C, appropriate for domestic heat technologies. It is demonstrated that energy storage efficiency can be maintained under cycling, with a constant latent heat storage capacity of 245 kJ/kg and a volumetric storage density of 314 MJ/m3. It was confirmed that the material should achieve a fully-melted state for stable supercooling. Finally, local cooling and retaining seed crystals through high pressure were highlighted as the most suitable basic principles for successful crystallization and heat release. This promising material can store energy for long periods without latent heat losses due to its stable subcooling. Latent heat can be released when required at any selected time and tem-perature just by a simple activation process.
November, 2022 · DOI: 10.1016/j.est.2022.105584
Materiales Ópticos Multifuncionales
Nanoantennas Patterned by Colloidal Lithography for Enhanced Nanophosphor Light Emission
Viana, JM; Romero, M; Lozano, G; Míguez, HACS Applied Nano Materials, 5(11) (2022) 16242-16249 DOI: 10.1021/acsanm.2c03258

Abstract
Transparent coatings made of rare-earth doped nanocrystals, also known as nanophosphors, feature efficient photoluminescence and excellent thermal and optical stabi l i t y . Herein, we demonstrate that the optical antennas prepared by colloidal lithography render thin nanophosphor films with a brighter emission. In particular, we fabricate gold nanostructures in the proximity of GdVO4:Eu3+ nanophosphors by metal evaporation using a mask made of a monolayer of polymer beads arranged in a triangular lattice. Optical modes supported by the antennas can be controlled by tuning the diameter of the polymer spheres in the colloidal mask, which determines the shape of the gold nanostructure, as confirmed by numerical simulations. Confocal microscopy reveals that metallic antennas induce brighter photoluminescence at specific spatial regions of the nanophosphor film at targeted frequencies as a result of the coupling between gold nanostructures and nanophosphors. Patterning of nanophosphor thin layers with arrays of metallic antennas offers an inexpensive nanophotonic solution to develop bright emitting coatings of interest for color conversion, labeling , or anti-counterfeiting.
November, 2022 · DOI: 10.1021/acsanm.2c03258
Reactividad de Sólidos
Reactive flash sintering of SrFe12O19 ceramic permanent magnets
Manchon-Gordon, AF; Sanchez-Jimenez, PE; Blazquez, JS; Perejon, A; Perez-Maqueda, LAJournal of Alloys and Compounds, 922 (2022) 166203 DOI: 10.1016/j.jallcom.2022.166203
Abstract
Reactive flash-sintering technique has been used in order to obtain strontium ferrite magnets from a mixture of SrCO3 and Fe2O3 commercial powders. This technique allows preparing sintered SrFe12O19 at a furnace temperature of just 973 K during just 2 min by applying a modest field of 40 V cm(-1), instead of the conventional sintering process employed in ferrite magnet manufacturing that demands high temperature and long dwell times. Analysis of structural and magnetic properties were performed as a function of time in which the flash event was held. Mossbauer spectra show the existence of five different kinds of local environments, confirming the formation of strontium hexaferrite. The resulting samples exhibit comparable magnetic properties to the state-of-the-art ferrite magnets. In particular, produced samples reach a coercivity of 0.4 T and a specific saturation magnetization of 70 Am-2 kg(-1).
November, 2022 · DOI: 10.1016/j.jallcom.2022.166203
Materiales de Diseño para la Energía y Medioambiente
Exploring the local environment of the engineered nanoclay Mica-4 under hydrothermal conditions using Eu(3+)as a luminescent probe
Martin-Rodriguez, R; Aguado, F; Alba, MD; Valiente, R; Pavon, E; Perdigon, ACJournal of Alloys and Compounds, 921 (2022) 166086 DOI: 10.1016/j.jallcom.2022.166086

Abstract
High charge mica Na4Al4Si4Mg6O20F4 , Mica-4, is a promising candidate as a filling material to immobilize high-level radioactive waste in deep geological repositories due to its extraordinary adsorption capacity. In contrast to traditional clay materials, the structural composition of this mica, with a high content of alu-minum in the tetrahedral sheet, enhances its chemical reactivity, favoring the formation of new crystalline phases under mild hydrothermal conditions, and thus providing a definitive isolation of the radionuclides in the engineered barrier. Moreover, this synthetic clay has some features that allow its use as an optical sensor by doping with luminescent rare earth cations such as Eu3+. In this paper we discuss the local structure of the nanoclay Mica-4 using Eu3+ as a local probe to track the physical and chemical modifica-tions under hydrothermal conditions. For that purpose, a set of hydrothermal experiments has been carried out heating Mica-4 and an aqueous Eu(NO3)(3) solution in a stainless steel reactor at different temperatures and times. Optical properties of the as-treated samples were characterized by spectroscopic measurements. The fine peak structure of emission and the relative intensity of different Eu3+ transitions as well as the luminescence lifetime have been correlated with the structure and composition of this nanoclay, and the interaction mechanisms between the lanthanide ions and the clay mineral at different temperatures and times. Special attention has been paid to understanding the role of the aluminum content, which may act as either an aggregating or dispersing agent, in the optical features and reactivity of the system.
November, 2022 · DOI: 10.1016/j.jallcom.2022.166086
Materiales de Diseño para la Energía y Medioambiente
Insights into the Impact of Activators on the 'Catalytic' Graphitization to Design Anode Materials for Lithium Ion Batteries
Hanhart, V; Frankenstein, L; Ramirez-Rico, J; Diozios, V; Winter, M; Gomez-Martin, A; Placke, TChemelectrochem, 9 (2022) e202200819 DOI: 10.1002/celc.202200819

Abstract
In this work, we systematically investigate the 'catalytic' graphitization of a biomass precursor (coffee ground) using 10-60 wt.% of the activator iron (III) chloride hexahydrate in a temperature range of 1000 degrees C-2400 degrees C. Special focus is put on the correlation of synthesis conditions, e.g., heat treatment temperature and mass fraction of iron chloride, with the electrochemical performance in carbon vertical bar vertical bar Li metal cells. The structural investigations of the materials reveal a positive impact of an increasing heat treatment temperature and/or mass fraction of inserted activator on the degree of graphitization and the delithiation capacity. However, a saturation point regarding the maximum degree of graphitization at 2000 degrees C and reversible capacity by the 'catalytic' graphitization approach using iron (III) chloride has been found. A maximum degree of graphitization of approximate to 69% could be reached by applying 2000 degrees C and 40 wt.% FeCl3 center dot 6H(2)O, resulting in a reversible capacity of 235 mAh g(-1).
November, 2022 · DOI: 10.1002/celc.202200819
Reactividad de Sólidos
Highly efficient electrical discharge machining of yttria-stabilized zirconia ceramics with graphene nanostructures as fillers
Muñoz-Ferreiro, C; Lopez-Pernia, C; Moriche, R; Gommeringer, A; Kern, F; Poyato, R; Gallardo-Lopez, AJournal of the European Ceramic Society, 42 (2022) 5943-5952 DOI: 10.1016/j.jeurceramsoc.2022.06.037

Abstract
Electrical-discharge machining (EDM) of advanced ceramics allows the miniaturization of parts with complex shapes. Since electrical conductivity is required, non-conductive ceramics need a conductive second phase. This work assesses the feasibility of industrial EDM in advanced yttria-stabilized tetragonal zirconia (3YTZP) composites with 20 vol% graphene nanostructures with different morphology using different EDM energies. The structural integrity of the graphene nanostructures, the roughness of the machined surfaces and the geometrical tolerances have been evaluated by Raman spectroscopy, confocal microscopy and scanning electron microscopy, showing that it is possible to obtain a stable and efficient EDM process in these composites using low electrode energies. The use of the largest and thickest graphene nanostructures led to the best performance in terms of EDM machinability, the smallest nanostructures produced the best surface finish for low electrode energy and the thinnest nanostructures allowed the highest material removal rate at medium energy in the composites.
October, 2022 · DOI: 10.1016/j.jeurceramsoc.2022.06.037
Reactividad de Sólidos
Comparative study of alkali activated cements based on metallurgical slags, in terms of technological properties developed
Gomez-Casero, MA; Perez-Villarejo, L; Sanchez-Soto, PJ; Eliche-Quesada, DSustainable Chemistry and Pharmacy, 29 (2022) 100746 DOI: 10.1016/j.scp.2022.100746

Abstract
In this work, an investigation on the use of two slags from different origins (electric arc furnace slag (EAFS) and copper slag (CS)) as raw materials in the manufacture of alkali-activated cements has been carried out. A comparison of the different mechanical properties developed by the alkaline activation of each raw material has been studied. Combination of 35 wt% potassium hydroxide (KOH) solution with different concentration (5, 8, 12 and 15 M) and 65 wt% potassium silicate (K2SiO3) solution was used as activating solution to manufacture alkali activated cements. The pastes were cured 24 h in a climatic chamber at 20 ºC at 90% of relative humidity, subsequently demoulded and cured at same condition during 1, 7, 28 and 90 days. Alkali activated materials have been characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The physical properties: bulk density, water absorption and apparent porosity, mechanical properties, flexural strength and compressive strength and thermal properties: thermal conductivity have been determined. The results indicate that two types of slags studied are a suitable source of aluminosilicates that can be activated for the manufacture of alkali-activated materials. These precursors are capable of developing high values of flexural and compressive strength and low values of thermal conductivity when optimal concentration of KOH was used. The optimal composition was developed when CS was utilized. Binders with CS and 12 M M ratio achieved compressive strength values up to 70 MPa.
October, 2022 · DOI: 10.1016/j.scp.2022.100746
Nanotecnología en Superficies y Plasma
Design and Characterization of ITO-Covered Resonant Nanopillars for Dual Optical and Electrochemical Sensing
Tramarin, L; Casquel, R; Gil-Rostra, J; Gonzalez-Martinez, MA; Herrero-Labrador, R; Murillo, AMM; Laguna, MF; Banuls, MJ; Gonzalez-Elipe, AR; Holgado, MChemosensors, 10 (2022) 393 DOI: 10.3390/chemosensors10100393
Abstract
In this work we present a dual optical and electrochemical sensor based on SiO2/Si3N4 resonant nanopillars covered with an indium tin oxide (ITO) thin film. A 25-30 nm thick ITO layer deposited by magnetron sputtering acts as an electrode when incorporated onto the nanostructured array, without compromising the optical sensing capability of the nanopillars. Bulk sensing performances before and after ITO deposition have been measured and compared in accordance with theoretical calculations. The electrochemical activity has been determined by the ferri/ferrocyanide redox reaction, showing a remarkably higher activity than that of flat thin films of similar ITO nominal thickness, and proving that the nanopillar system covered by ITO presents electrical continuity. A label-free optical biological detection has been performed, where the presence of amyloid-beta has been detected through an immunoassay enhanced with gold nanoparticles. Again, the experimental results have been corroborated by theoretical simulations. We have demonstrated that ITO can be a beneficial component for resonant nanopillars sensors by adding potential electrochemical sensing capabilities, without significantly altering their optical properties. We foresee that resonant nanopillars coated with a continuous ITO film could be used for simultaneous optical and electrochemical biosensing, improving the robustness of biomolecular identification.
October, 2022 · DOI: 10.3390/chemosensors10100393
Materiales Ópticos Multifuncionales
Enhanced red-UC luminescence through Ce3+ co-doping in NaBiF4:Yb3+/Ho3+(Er3+)/Ce3+ phosphors prepared by ultrafast coprecipitation approach
Giordano, L; Du, H; Castaing, V; Luan, F; Guo, D; Viana, BOptical Materials X, 16 (2022) 100199 DOI: 10.1016/j.omx.2022.100199
Abstract
Series of Yb3+/Ho3+(Er3+)/Ce3+ co-doped NaBiF4 phosphors were synthesized through an ultrafast co-precipitation reaction technique at room temperature. The effect of the Ce3+ ions on the crystal structure and upconversion (UC) luminescence properties of the studied samples were investigated in detail. FTIR and XPS demonstrated the pre-formation of NaBiF4 and the introduction of Yb3+, Ho3+, Er3+ and Ce3+ all as dopants in the host materials. Under 980 nm excitation, NaBiF4:Yb3+,Ho3+(Er3+),Ce3+performed the characteristic emission of the activator ion, and the introduction of Ce3+ did not change the emission wavelengths, only the relative intensities. Due to partial good energy overlap when 2F7/2 Ce3+ manifold is populated, raising Ce3+ ions concentration enhanced the red UC emission versus green UC emission but also lead to significant decrease in the average lifetimes of all monitored emissions for Ho3+ and Er3+. These lifetime decreases are explained by the energy loss in non-radiative pathways after the introduction of Ce3+. In addition, the green to yellow color emission change through addition of Ce3+ was explored in NaBiF4: Yb3+,Ho3+,Ce3+ to propose a novel application in two-level anti-counterfeiting.
October, 2022 · DOI: 10.1016/j.omx.2022.100199
Química de Superficies y Catálisis
Ni-Phosphide catalysts as versatile systems for gas-phase CO2 conversion: Impact of the support and evidences of structure-sensitivity
Zhang, Q; Pastor-Perez, L; Villora-Pico, JJ; Joyce, M; Sepulveda-Escribano, A; Duyar, MS; Reina, TRFuel, 323 (2022) 124301 DOI: 10.1016/j.fuel.2022.124301

Abstract
We report for the first time the support dependent activity and selectivity of Ni-rich nickel phosphide catalysts for CO2 hydrogenation. New catalysts for CO2 hydrogenation are needed to commercialise the reverse water-gas shift reaction (RWGS) which can feed captured carbon as feedstock for traditionally fossil fuel-based processes, as well as to develop flexible power-to-gas schemes that can synthesise chemicals on demand using surplus renewable energy and captured CO2. Here we show that Ni2P/SiO2 is a highly selective catalyst for RWGS, producing over 80% CO in the full temperature range of 350-750 degrees C. This indicates a high degree of suppression of the methanation reaction by phosphide formation, as Ni catalysts are known for their high methanation activity. This is shown to not simply be a site blocking effect, but to arise from the formation of a new more active site for RWGS. When supported on Al2O3 or CeAl, the dominant phase of as synthesized catalysts is Ni12P5. These Ni12P5 catalysts behave very differently compared to Ni2P/SiO2, and show activity for methanation at low temperatures with a switchover to RWGS at higher temperatures (reaching or approaching thermodynamic equilibrium behaviour). This switchable activity is interesting for applications where flexibility in distributed chemicals production from captured CO2 can be desirable. Both Ni12P5/Al2O3 and Ni12P5/CeAl show excellent stability over 100 h on stream, where they switch between methanation and RWGS reactions at 50-70% conversion. Catalysts are characterized before and after reactions via X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), temperature-programmed reduction and oxidation (TPR, TPO), Transmission Electron Microscopy (TEM), and BET surface area measurement. After reaction, Ni2P/SiO(2 )shows the emergence of a crystalline Ni12P5 phase while Ni12P5/Al2O3 and Ni12P5/CeAl both show the crystalline Ni3P phase. While stable activity of the latter catalysts is demonstrated via extended testing, this Ni enrichment in all phosphide catalysts shows the dynamic nature of the catalysts during operation. Moreover, it demonstrates that both the support and the phosphide phase play a key role in determining selectivity towards CO or CH4.
September, 2022 · DOI: 10.1016/j.fuel.2022.124301
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Unraveling the Mo/HZSM-5 reduction pre-treatment effect on methane dehydroaromatization reaction
Lopez-Martin, A; Caballero, A; Colon, GApplied Catalysis B-Environmental, 312 (2022) 121382 DOI: 10.1016/j.apcatb.2022.121382

Abstract
Reduction pre-treatment at different temperatures were performed over Mo/HZSM-5 system before methane dehydroaromatiztion reaction. We have shown the crucial effect of reduction temperature on the final catalytic performance. Outstanding improvement in the aromatics conversion has been attained. Thus, H-2 formation form methane cracking reaction seems to be hindered for pre-treated catalysts. As a consequence, the deposition of coke in these samples appeared also notably suppressed. The optimum performance has been achieved for reduction pre-treatment at 550 degrees C. For this temperature, we have observed that the fraction of reduced Mo species is higher.
September, 2022 · DOI: 10.1016/j.apcatb.2022.121382
Química de Superficies y Catálisis
Sustainable routes for acetic acid production: Traditional processes vs a low-carbon, biogas-based strategy
Martin-Espejo, JL; Gandara-Loe, J; Odriozola, JA; Reima, TR; Pastor-Pérez, LScience of the Total Environment, 840 (2022) 156663 DOI: 10.1016/j.scitotenv.2022.156663

Abstract
The conversion of biogas, mainly formed of CO2 and CH4, into high-value platform chemicals is increasing attention in a context of low-carbon societies. In this new paradigm, acetic acid (AA) is deemed as an interesting product for the chemical industry. Herein we present a fresh overview of the current manufacturing approaches, compared to potential low-carbon alternatives. The use of biogas as primary feedstock to produce acetic acid is an auspicious alternative, representing a step-ahead on carbon-neutral industrial processes. Within the spirit of a circular economy, we propose and analyse a new BIO-strategy with two noteworthy pathways to potentially lower the environmental impact. The generation of syngas via dry reforming (DRM) combined with CO2 utilisation offers a way to produce acetic acid in a two-step approach (BIO-Indirect route), replacing the conventional, petroleum-derived steam reforming process. The most recent advances on catalyst design and technology are discussed. On the other hand, the BIO-Direct route offers a ground-breaking, atom-efficient way to directly generate acetic acid from biogas. Nevertheless, due to thermodynamic restrictions, the use of plasma technology is needed to directly produce acetic acid. This very promising approach is still in an early stage. Particularly, progress in catalyst design is mandatory to enable low-carbon routes for acetic acid production.
September, 2022 · DOI: 10.1016/j.scitotenv.2022.156663
Materiales Avanzados
Pre-Roman and Republican amphorae (III-I centuries b.C.) from production contexts of the Guadalquivir Basin: technical and compositional characterization
Moreno-Megías, V.; García-Fernández, F.J.; Martín-del-Río, J.J.; Borreguero-Cid, M.; Sánchez-Soto, P.J.Boletín de la Sociedad Española de Cerámica y Vidrio, 61 (2022) 498-515 DOI: 10.1016/j.bsecv.2021.03.008
Abstract
The present work consists of an archaeometric investigation concerning ceramic samples, mostly unpublished, of the III-I centuries b.C. They were found in connection with kilns of the city of Sevilla (Archbishop's Palace) and the countryside (Arrabal zone, Carmona). They are identified with evolved variations of Iron Age amphorae of Punic and Turdetanian tradition, or already Roman typologies. The main objectives of this research include their technological and compositional characterization as well as the comparison of the characteristics of each manufacture tradition.
An assemblage of 13 samples has been studied through petrographic analysis of thin sections, chemical analysis (X-ray fluorescence) and mineralogical analysis (X-ray diffraction). The chemical results showed the silico-aluminous and calcitic character of the samples, with variable contents of iron oxide as well as other minor elements and traces. The statistical treatment of the data by multivariant analysis has differentiated 3 conglomerates and one sample as an outsider. The mineralogical analysis has identified 8 crystalline phases, several of them already present in the raw materials and others formed by thermal treatment. It is interesting to note the illite, identified as dehydroxylated phase, anorthite, diopside and gehlenite. The petrographical analysis has identified 3 different petro-groups, which are correlated by a compositional point of view with the original context of the samples. Thus, according to these results, it has been possible to distinguish the manufactures of Sevilla from the Roman shapes, the common ware and the imitation types of Carmona.
It has been discussed the possible solid-state reactions which yielded the crystalline phases identified by X-ray diffraction, besides an estimation of firing temperatures between 820-850 degrees C in an oxidant atmosphere. Finally, the possible sources for the raw materials used in the fabrication of these amphorae have been proposed in the Guadalquivir River valley, considering their illitic-calcitic characteristics.
September, 2022 · DOI: 10.1016/j.bsecv.2021.03.008
Química de Superficies y Catálisis
Hydrogen production from landfill biogas: Profitability analysis of a real case study
Vidal-Barrero, F; Baena-Moreno, FM; Preciado-Cardenas, C; Villanueva-Perales, A; Reina, TRFuel, 324 (2022) 124438 DOI: 10.1016/j.fuel.2022.124438
Abstract
Hydrogen is not only considered as a cornerstone within renewable energy portfolio but it is also a key enabler for CO2 valorisation being a central resource for industrial decarbonization. This work evaluates the profitability of hydrogen production via combined biogas reforming and water-gas shift reaction, based on a real case scenario for landfill biogas plant in Seville (Spain). A techno-economic model was developed based on a process model and the discounted cash-flow method. A biogas flow of 700 m(3)/h (input given by the landfill biogas plant) was used as plant size and the analysis was carried out for two different cases: (1) use of already available energy sources at the industrial plant, and (2) solar energy generation to power the process. The economic outputs obtained showed that under the current circumstances, this hydrogen production route is not profitable. The main reason is the relatively low current hydrogen prices which comes from fossil fuels. A revenues analysis indicates that hydrogen from biogas selling prices between 2.9 and 5.7 euro/kg would be needed to reach profitability, which are considerably higher than the current hydrogen cost (1.7 euro/kg). A subsidy scheme is suggested to improve the competitiveness of this hydrogen production process in the short-medium term. A cost analysis is also performed, revealing that electricity prices and investment costs have a high impact on the total share (23-40% and 8-22%, respectively). Other potential costs reduction such as catalyst, labour and manteinance & overhead are also evaluated, showing that cutting-down production costs is mandatory to unlock the potential of hydrogen generation from biogas. Our work showcases the techno-economic challenge that green energy policies face in the path toward sustainable societies.
September, 2022 · DOI: 10.1016/j.fuel.2022.124438
Materiales para Bioingeniería y Regeneración Tisular
Sol-Gel Synthesis of Endodontic Cements: Post-Synthesis Treatment to Improve Setting Performance and Bioactivity
Song, X; Diaz-Cuenca, AMaterials, 15 (2022) 6051 DOI: 10.3390/ma15176051
Abstract
The sol-gel process is a wet chemical technique that allows very fine control of the composition, microstructure, and final textural properties of materials, and has great potential for the synthesis of endodontic cements with improved properties. In this work, the influence of different sol-gel synthesis variables on the preparation of endodontic cement based on calcium silicate with Ca/Si stoichiometry equal to 3 was studied. Starting from the most optimal hydraulic composition selected, a novel second post-synthesis treatment using ethanol was essayed. The effects of the tested variables were analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption, and Gillmore needles to determine the setting time and simulated body fluid (SBF) immersion to measure the bioactive response in vitro. The results indicated that the sol-gel technique is effective in obtaining bioactive endodontic cements (BECs) with high content of the hydraulic compound tricalcium silicate (C3S) in its triclinic polymorph. The implementation of a novel post-synthesis treatment at room temperature using ethanol allows obtaining a final BEC product with a finer particle size and a higher CaCO3 content, which results in an improved material in terms of setting time and bioactive response.
September, 2022 · DOI: 10.3390/ma15176051
Tribología y Protección de Superficies
Influence of the carbon incorporation on the mechanical properties of TiB2 thin films prepared by HiPIMS
Sala, N; Abad, MD; Sanchez-Lopez, JC; Crugeira, F; Ramos-Masana, A; Colominas, CInternational Journal of Refractory Metals & Hard Materials, 107 (2022) 105884 DOI: 10.1016/j.ijrmhm.2022.105884
Abstract
Nanostructured TiB2 and TiBC thin films with carbon contents up to 11 at. % were prepared by physical vapor deposition using high power impulse magnetron sputtering (HiPIMS) technology. The influence of carbon incorporation during the deposition of TiB2 coatings was investigated on the chemical composition, microstructure and mechanical properties by means of scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), nanoindentation, scratch test, calotest and adhesion Daimler-Benz test. The results indicated that small additions of carbon up to 3 at. % improved the mechanical behavior and increased the adhesion of the TiB2 thin films. Hardnesses up to 37 GPa were reached and the adhesion of the coating to AISI D2 steel substrates increased from 11 to 18 N. XRD and XPS results showed that the carbon atoms are either occupying interstitial sites within the hexagonal structure of the TiB2 or forming bonds with titanium and boron atoms. The preferred orientation of the films determined by XRD also changed with the increasing carbon content in the (001) crystalline plane.
September, 2022 · DOI: 10.1016/j.ijrmhm.2022.105884
Nanotecnología en Superficies y Plasma
Multiscale Kinetic Monte Carlo Simulation of Self-Organized Growth of GaN/AlN Quantum Dots
Budagosky, JA; García-Cristobal, ANanomaterials, 12 (2022) 3052 DOI: 10.3390/nano12173052
Abstract
A three-dimensional kinetic Monte Carlo methodology is developed to study the strained epitaxial growth of wurtzite GaN/AlN quantum dots. It describes the kinetics of effective GaN adatoms on an hexagonal lattice. The elastic strain energy is evaluated by a purposely devised procedure: first, we take advantage of the fact that the deformation in a lattice-mismatched heterostructure is equivalent to that obtained by assuming that one of the regions of the system is subjected to a properly chosen uniform stress (Eshelby inclusion concept), and then the strain is obtained by applying the Green's function method. The standard Monte Carlo method has been modified to implement a multiscale algorithm that allows the isolated adatoms to perform long diffusion jumps. With these state-of-the art modifications, it is possible to perform efficiently simulations over large areas and long elapsed times. We have taylored the model to the conditions of molecular beam epitaxy under N-rich conditions. The corresponding simulations reproduce the different stages of the Stranski-Krastanov transition, showing quantitative agreement with the experimental findings concerning the critical deposition, and island size and density. The influence of growth parameters, such as the relative fluxes of Ga and N and the substrate temperature, is also studied and found to be consistent with the experimental observations. In addition, the growth of stacked layers of quantum dots is also simulated and the conditions for their vertical alignment and homogenization are illustrated. In summary, the developed methodology allows one to reproduce the main features of the self-organized quantum dot growth and to understand the microscopic mechanisms at play.
September, 2022 · DOI: 10.3390/nano12173052
Nanotecnología en Superficies y Plasma
Optimization of anion exchange membrane water electrolyzers using ionomer-free electrodes
Lopez-Fernandez, E; Gomez-Sacedon, C; Gil-Rostra, J; Espinos, JP; Brey, JJ; Gonzalez-Elipe, AR; de Lucas-Consuegra, A.; Yubero, FRenewable Energy, 197 (2022) 1183-1191 DOI: 10.1016/j.renene.2022.08.013

Abstract
This work is carried out in the context of the anion exchange membrane water electrolysis (AEMWE) and pursuits to determine the influence of different cell components on the global electrochemical performance. Ionomer-free electrodes consisting of anodic Ni-Fe and cathodic Ni electrocatalysts deposited by magnetron sputtering in an oblique angle deposition configuration were utilized for this study. In addition to the characteristics and equivalent thickness of the electrocatalysts, other factors affecting the efficiency that have been considered in this study encompass the type of gas diffusion layer (GDLs), including carbon paper and stainless-steel fiber paper supports, and several commercial anion exchange membranes. The electrocatalytic performances in both a threeelectrode and complete single cell AEMWE set-ups, together with the physico-chemical characterization of the electrodes before and after operation, have served to select the optimum components for the utilized cell configuration. Thus, current densities of 670 mA cm-2, at polarization voltage of 2.2 V, 1.0 M KOH electrolyte and 40 degrees C were obtained in a membrane electrode assembly. A seven days chronopotentiometry experiment at a fixed current of 400 mA cm-2 demonstrated a noticeable stability of this type of AEMWE cells incorporating ionomer-free electrodes.
September, 2022 · DOI: 10.1016/j.renene.2022.08.013
Reactividad de Sólidos
Oxygen production routes assessment for oxy-fuel combustion
Garcia-Luna, S; Ortiz, C; Carro, A; Chacartegui, R; Perez-Maqueda, LAEnergy, 254 (2022) 124303 DOI: 10.1016/j.energy.2022.124303
Abstract
Oxyfuel combustion is a promising alternative to decarbonize the power sector. However, the main barrier to commercial deployment of the technology is the high energy consumption associated with oxygen production (-200-300 kWh per ton of O-2), which penalizes the thermal-to-electric efficiency of 8.5-12% compared to traditional air combustion plants. Typically, oxygen is obtained from a cryogenic air separation process. However, other technologies have been gaining momentum in recent years, such as membrane technologies, chemical looping air separation, and renewable-driven electrolysis. The present work evaluates all these options for O-2 production to retrofit a 550 MWe coal-fired power plant with oxyfuel combustion. A techno-economic assessment is carried out to estimate the energy penalty, the O-2 production cost (V/ton) and the Levelized Cost of Electricity. The best results are obtained by combining oxygen transport membranes and electrolysis since the energy consumption has been reduced to 98.56 kWh/ton of O(2, )decreasing by 59.31% the cryogenic distillation energy consumption (242.24 kWh/ ton O2), reducing the overall energy penalty compared to cryogenic air separation from 8.88% points to 7.56%points. The oxygen transport membrane presents the lowest cost of electricity in retrofitting cases, 51.48 $/MWh, while cryogenic distillation estimated cost is 52.7 $/MWh. Their costs of avoided CO2 are 31.79 $/ton CO2 and 34.15 $/ton CO2 respectively.
September, 2022 · DOI: 10.1016/j.energy.2022.124303
Reactividad de Sólidos
Low-pressure calcination to enhance the calcium looping process for thermochemical energy storage
Ortiz, C; Carro, A; Chacartegui, R; Valverde, JM; Perejon, A; Sánchez-Jiménez, PE; Pérez-Maqueda, LAJournal of Cleaner Production, 363 (2022) 132295 DOI: 10.1016/j.jclepro.2022.132295
Abstract
The Calcium-Looping (CaL) process, based on the multicyclic calcination-carbonation of CaCO3/CaO, is considered a promising Thermochemical Energy Storage (TCES) technology to be integrated into Concentrating Solar Power (CSP) plants. This work proposes a novel CaL integration that operates at low-pressure calcination under pure CO2 and a moderated temperature. Low-pressure calcination (0.01 bar) provides a suitable solution to mitigate CaO sintering and its consequent loss of reactivity in the carbonation stage. Since the temperature for quick calcination in a pure CO2 atmosphere is decreased (from around 950 °C at 1 bar to 765 °C at 0.01 bar), the energy losses at the receiver are minimised. In addition, a reduced calcination temperature allows for the use of metallic receivers already tested at the MW-scale, which significantly increases the CSP-CaL integration reliability. Moreover, multicycle CaO reactivity is promoted in short residence times, allowing the use of a simpler reactor design. Furthermore, there is an increase of 85% in the energy storage density of the system. The proposed plant proposes a smooth integration of the CaL process in CSP plants, with a moderate storage level and supported by a natural gas backup system (solar share higher than 50%). The results show that the solar thermal-to electric efficiency is above 30%.
August, 2022 · DOI: 10.1016/j.jclepro.2022.132295
Química de Superficies y Catálisis
Structure effect of modified biochar in Ru/C catalysts for sugar mixture hydrogenation
Santos, JL; Sanz-Moral, LM; Aho, A; Ivanova, S; Murzin, DY; Centeno, MABiomass & Bioenergy, 163 (2022) 106504 DOI: 10.1016/j.biombioe.2022.106504

Abstract
This study deals with the production and activation of biochars and their use as supports for a series of ruthenium catalysts for hydrogenation of L-arabinose/D-galactose sugar mixture. The synthesized biochars differ in physicochemical properties and surface chemistry influencing ruthenium metal uptake and dispersion and as a consequence its catalytic behaviour. Selectivity exceeding 95% was observed for both hexitols. The catalytic performance of the prepared Ru supported catalysts is also compared to the already known Ru/activated carbon commercial catalyst.
August, 2022 · DOI: 10.1016/j.biombioe.2022.106504
Química de Superficies y Catálisis
Recent advances on gas-phase CO2 conversion: Catalysis design and chemical processes to close the carbon cycle
Torres-Sempere, G; Pastor-Perez, L; Odriozola, JA; Yu, J; Duran-Olivencia, FJ; Bobadilla, LF; Reina, TRCurrent Opinion in Green andd Sustainable Chemistry, 36 (2022) 100647 DOI: 10.1016/j.cogsc.2022.100647
Abstract
Chemical CO2 recycling in the gas phase constitutes a straightforward approach for effective CO2 conversion to added-value products like syngas or synthetic methane. In this scenario, some traditional processes such as the dry and bi-reforming of methane, the CO2 methanation and the reverse water-gas shift have gained a renewed interest from the CO2 utilisation perspective. Indeed, these reactions represent flexible routes to upgrade CO2 and their application at an industrial scale could substantially reduce CO2 emissions. The bottleneck for the implementation of these processes at the commercial level is the development of highly active and robust heterogeneous catalysts able to overcome CO2 activation and deliver sufficient amounts of the upgrading products (i.e. syngas or synthetic natural gas) at the desired operating conditions. This review paper gathers the most recent advances in the design of new catalytic formulations for chemical CO2 recycling in the gas phase and constitutes an overview for experts and newcomers in the field to get fundamental insights into this emerging branch of low-carbon technologies.
August, 2022 · DOI: 10.1016/j.cogsc.2022.100647
Reactividad de Sólidos
On the adsorption properties and applications of mixed-linker MOFs based on HKUST-1
Puerto-Rodríguez, M; López-Cartes, C; Ayala, RJournal of Solid State Chemistry, 312 (2022) 123260 DOI: 10.1016/j.jssc.2022.123260

Abstract
Different mixed-linker MOFs based on HKUST-1 have been successfully synthesized using BtTC (1,2,4,5-benzenetetracarboxylate) and BDC (1,4-benzenedicarboxylate) as modulator ligands. These MOFs maintain the HKUST-1 structure up to 25% and 50% of trimesic acid replacing with BtTC and BDC ligands, respectively. A low percentage of modulator ligand provokes an increasing of the MOF surface area keeping its microporosity whereas a higher content of BtTC induces mesoposority in the samples. The adsorption of moisture ambient or vapour iodine reveals that there is a relation between the surface area and the capacity of adsorption of the samples. However, this relation is not found in the experiments of Congo Red removal from aqueous and ethanol solutions. The pH of the solutions has a significant effect on the adsorption capacity of the samples.
August, 2022 · DOI: 10.1016/j.jssc.2022.123260
Nanotecnología en Superficies y Plasma
One-Dimensional Photonic Crystal for Surface Mode Polarization Control
Mogni, E; Pellegrini, G; Gil-Rostra, J; Yubero, F; Simone, G; Fossati, S; Dostalek, J; Vazquez, RM; Osellame, R; Celebrano, M; Finazzi, M; Biagioni, PAdvanced Optical Materials, (2022) 2200759 DOI: 10.1002/adom.202200759
Abstract
Bloch surface waves sustained by truncated 1D photonic crystals (1DPCs) are well known tools for surface-enhanced spectroscopy. They provide strongly confined fields with uniform distribution over a large surface area, a characteristic exploited in standard refractometric sensing. However, their application to polarization-sensitive investigations is not straightforward because the transverse electric (TE) and magnetic (TM) surface modes possess distinct dispersion relations, therefore their relative phase is not conserved along propagation and the polarization state of any wave obtained by combining these modes is ill-defined. In this work, a novel design of a 1DPC is realized in which the TE and TM modes exhibit the same phase velocity over a broadband spectral range and thus their dispersion relations overlap. The capability to simultaneously excite TE and TM modes with a well-defined phase relation allows the generation of surface waves with a controlled polarization state. This paves the way to polarization-resolved surface-enhanced analysis, including, for example, linear and circular dichroism spectroscopy of grafted molecular layers at the photonic crystal surface.
August, 2022 · DOI: 10.1002/adom.202200759
Química de Superficies y Catálisis
Emerging natural and tailored perovskite-type mixed oxides-based catalysts for CO2 conversions
Wu, J; Ye, RP; Xu, DJ; Wan, LZ; Reina, TR; Sun, H; Ni, Y; Zhou, ZF; Deng, XAFrontiers in Chemistry, 10 (2022) 961355 DOI: 10.3389/fchem.2022.961355
Abstract
The rapid economic and societal development have led to unprecedented energy demand and consumption resulting in the harmful emission of pollutants. Hence, the conversion of greenhouse gases into valuable chemicals and fuels has become an urgent challenge for the scientific community. In recent decades, perovskite-type mixed oxide-based catalysts have attracted significant attention as efficient CO2 conversion catalysts due to the characteristics of both reversible oxygen storage capacity and stable structure compared to traditional oxide-supported catalysts. In this review, we hand over a comprehensive overview of the research for CO2 conversion by these emerging perovskite-type mixed oxide-based catalysts. Three main CO2 conversions, namely reverse water gas shift reaction, CO2 methanation, and CO2 reforming of methane have been introduced over perovskite-type mixed oxide-based catalysts and their reaction mechanisms. Different approaches for promoting activity and resisting carbon deposition have also been discussed, involving increased oxygen vacancies, enhanced dispersion of active metal, and fine-tuning strong metal-support interactions. Finally, the current challenges are mooted, and we have proposed future research prospects in this field to inspire more sensational breakthroughs in the material and environment fields.
August, 2022 · DOI: 10.3389/fchem.2022.961355
Reactividad de Sólidos
Overlooked pitfalls in CaO carbonation kinetics studies nearby equilibrium: Instrumental effects on calculated kinetic rate constants
Arcenegui-Troya, J; Duran-Martin, JD; Perejon, A; Valverde, JM; Maqueda, LAP; Jimenez, PESAlexandria Engineering Journal, 61 (2022) 6129-6138 DOI: 10.1016/j.aej.2021.11.043
Abstract
Due to its technological applications, such as CO2 capture, CaO carbonation kinetics has been extensively studied using a wide array of methods and experimental conditions. A complete understanding of carbonation kinetics is key to optimizing the operating conditions as well as to correctly design the carbonation reactor. However, there is yet no consensus on the reaction model and kinetic parameters that can best describe the CaO carbonation reaction. For instance, the value of the activation energy proposed in different works can vary up to 300%. In this work, we demonstrate that the strong influence of the thermodynamic equilibrium on CaO carbonation kinetics demands careful control of the experimental conditions to obtain meaningful kinetic parameters. Specifically, we explore the influence of three experimental parameters on carbonation kinetics: the gas flow rate, the CO2 partial pressure and the time required to fill the reactor after a gas change. We demonstrate that disregarding these aspects may lead to bogus conclusions on reaction kinetics, which could partly explain the considerable discrepancies found in the literature. The conclusions of this work are not only applicable to the process and experimental setup studied here but also to any study that involves the use of gas flow to drive a reaction.
August, 2022 · DOI: 10.1016/j.aej.2021.11.043
Materiales Avanzados
Chemical, Radiometric and Mechanical Characterization of Commercial Polymeric Films for Greenhouse Applications
Franco, JE; Rodríguez-Arroyo, JA; Ortiz, IM; Sánchez-Soto, PJ; Garzón, E; Lao, MTMaterials, 15 (2022) 5532 DOI: 10.3390/ma15165532
Abstract
In the agricultural sector, companies involved in the production of plastic greenhouses are currently searching for a suitable covering adapted for every climate in the world. For this purpose, this research work has determined the chemical, radiometric and mechanical properties of 53 polymeric films samples from Europe and South America. The chemical tests carried out with these samples were elemental analysis (C, H and N) and FT-IR spectrometry. The radiometric properties here studied were the transmission, absorption and reflection coefficients along the spectrum between 300 and 1100 nm. For the mechanical properties, tensile strength, tear strength and dart impact strength, tests were carried out. Finally, all these data were collected, and a multivariate statistical analysis was carried out using the SPSS statistical to group the samples into statistical groups adapted to specific climatic regions. The elemental analysis and FT-IR spectrometry allowed group the samples into nine groups. The samples were grouped according to their chemical (elemental analysis), radiometric and mechanical properties by multivariate analysis. The dendrogram separated five very different groups in terms of number of samples. These groups have specific chemical, radiometric and mechanical characteristics that separate them from the rest. These groups make it possible to narrow down the applications and correlate with the radiometric properties to see in which geographical area of the world they are most effective in increasing yields and achieving higher quality production.
August, 2022 · DOI: 10.3390/ma15165532
Química de Superficies y Catálisis
Feasibility of switchable dual function materials as a flexible technology for CO2 capture and utilisation and evidence of passive direct air capture
Merkouri, LP; Reina, TR; Duyar, MSNanoscale, 14 (2022) 12620-12637 DOI: 10.1039/d2nr02688k

Abstract
The feasibility of a Dual Function Material (DFM) with a versatile catalyst offering switchable chemical synthesis from carbon dioxide (CO2) was demonstrated for the first time, showing evidence of the ability of these DFMs to passively capture CO2 directly from the air as well. These DFMs open up possibilities in flexible chemical production from dilute sources of CO2, through a combination of CO2 adsorption and subsequent chemical transformation (methanation, reverse water gas shift or dry reforming of methane). Combinations of Ni Ru bimetallic catalyst with Na2O, K2O or CaO adsorbent were supported on CeO2-Al2O3 to develop flexible DFMs. The designed multicomponent materials were shown to reversibly adsorb CO2 between the 350 and 650 degrees C temperature range and were easily regenerated by an inert gas purge stream. The components of the flexible DFMs showed a high degree of interaction with each other, which evidently enhanced their CO2 capture performance ranging from 0.14 to 0.49 mol kg(-1). It was shown that captured CO2 could be converted into useful products through either CO2 methanation, reverse water-gas shift (RWGS) or dry reforming of methane (DRM), which provides flexibility in terms of co-reactant (hydrogen vs. methane) and end product (synthetic natural gas, syngas or CO) by adjusting reaction conditions. The best DFM was the one containing CaO, producing 104 mu mol of CH4 per kg(DFM) in CO2 methanation, 58 mu mol of CO per kg(DFM) in RWGS and 338 mu mol of CO per kg(DFM) in DRM.
August, 2022 · DOI: 10.1039/d2nr02688k
Materiales Avanzados
Assessment of construction and demolition wastes (CDWs) as raw materials for the manufacture of low-strength concrete and bases and sub-bases of roads
Garzon, E; Martinez-Martinez, S; Perez-Villarrejo, L; Sanchez-Soto, PJMaterials Letters, 320 (2022) 132343 DOI: 10.1016/j.matlet.2022.132343
Abstract
A chemical (XRF) and mineralogical (XRD) characterisation has been carried out, as well as the determination of the main properties, of construction and demolition wastes (CDWs). This waste has been applied as recycled aggregate. The objective was to search for its reuse for the manufacture of concrete and road bases and sub-bases. Chemical analysis revealed the presence of SiO2 (39.13 wt%) and Al2O3 (9.55 wt%) from quartz and some silicates, and gypsum. The content of CaO (21.42 wt%) was associated with calcite and dolomite. The materials' properties have suggested that the particle sizes are not inside the typical interval fixed in the Spanish normative. It can be reused as esplanades or sub-bases of roads and highways, since it is a granular material with a very high California Bearing Ratio (CBR value is 36). It was concluded that the use of CDWs as a substitute of sand for the manufacture of concrete can only be used in percentages lower than 10 wt% producing low-strength concrete.
August, 2022 · DOI: 10.1016/j.matlet.2022.132343
Materiales Coloidales
Outstanding MRI contrast with dysprosium phosphate nanoparticles of tuneable size
Gómez-González, E.; Caro, C.; García-Martín, ML; Becerro, AI; Ocaña, M.Nanoscale, 14 (2022) 11461-11470 DOI: 10.1039/d2nr02630a

Abstract
The use of high-field magnets for magnetic resonance imaging (MRI) is expected to experience the fastest growth rate during the present decade. Although several CAs for MRI scanners using high magnetic fields have been reported, they are mostly based on fluoride matrices, which are known for their low chemical stability in aqueous suspensions. Chemically stable MRI CAs for high-field magnets are therefore needed to enable the advances in MRI technique. Herein, we synthesized uniform DyPO4 nanoparticles (NPs) with tuneable sizes between 23 and 57 nm using homogeneous precipitation in butanol. The NPs were successfully functionalized with polyacrylic acid (PAA) and showed good colloidal stability in aqueous suspensions. Chemical stability was also assessed in PBS, showing negligible solubility. The effect of particle size on the transversal relaxivity value (r(2)) was further explored at 9.4 T, finding a clear increase in r(2) with particle size. The r(2) value found for the largest NPs was 516 mM(-1) s(-1), which is, to the best of our knowledge, the highest r(2) value ever reported at 9.4 T for any Dy-based nanometric particles in the literature. Finally, the latter NPs were submitted to biosafety studies after polyethylene glycol (PEG) functionalization. Cell morphology, induction of necrotic/late apoptotic cells, and mitochondrial activity were thoroughly analyzed. The results clearly indicated negligible toxicity effects under the assayed conditions. Short- and long-term in vivo pharmacokinetics of the intravenously injected NPs were assessed by dynamic T-2-weighted MRI and quantitative T-2 mapping, revealing faster liver than spleen uptake, while no accumulation was observed in the kidneys. Finally, no histopathological changes were observed in any of the studied organs, including the liver, kidney, spleen, and lung, which provide further evidence of the biocompatibility of DyPO4 NPs and, therefore, their suitability as bioimaging probes.
August, 2022 · DOI: 10.1039/d2nr02630a
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Shepherding reaction intermediates to optimize H-2 yield using composite-doped TiO2-based photocatalysts
Barba-Nieto, I.; Colon, G; Fernández-García, M; Kubacka, AChemical Engineering Journal, 442 (2022) 136333 DOI: 10.1016/j.cej.2022.136333
Abstract
Optimization of Pt-promoted TiO2-based is key to promote the photocatalytic production of hydrogen using sacrificial alcohol molecules. Combination of doping and surface decoration of the mentioned base photoactive material is here exploited to maximize hydrogen yield. Using the quantum efficiency parameter, it is shown that the resulting composite system can boost activity up to 7.3 times within the whole methanol:water mixture ratio, yielding quantum efficiencies in the ca. 13-16 % range. The key role of the different components in generating charge carrier species and their use to trigger the sacrificial molecule evolution and control reaction kinetics are examined through an in-situ spectroscopic study. The study unveils the complex reaction mechanism, with generation of C1 to C3 molecules from different carbon-containing radicals, and interprets the physical origin of the huge H2 production enhancement occurring in doped-composite titania-based catalysts.
August, 2022 · DOI: 10.1016/j.cej.2022.136333
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Tuning the co-catalyst loading for the optimization of thermo-photocatalytic hydrogen production over Cu/TiO2
Platero, F; Caballero, A; Colon, GApplied Catalysis A-General, 643 (2022) 118804 DOI: 10.1016/j.apcata.2022.118804

Abstract
We have optimized the H-2 production by methanol thermo-photocatalytic reforming in the gas phase using Cu/TiO2 catalyst by tuning metal loading. Metal co-catalyst has been deposited by means of chemical reduction deposition. We have stated that thermo- and thermo-photocatalytic process leads to a notable H-2 production at 200 C. By in-situ FTIR studies we evidenced that formate formation follows a different evolution depending on the reforming experiment. These surface formate would lead to CO formation through dehydration reaction. At higher Cu content the low CO selectivity denote that water-gas-shift reaction would predominate and exalt H-2 yield. Thus, different optimum Cu content is found for each reforming experiment. While for the photocatalytic reforming Cu/TiO2 (2 wt%) is the best catalyst of the series, we should increase the Cu content to Cu/TiO2 (5 wt%) to achieve the optimum performance for thermo-photocatalytic reforming of methanol.
August, 2022 · DOI: 10.1016/j.apcata.2022.118804
Química de Superficies y Catálisis
Catalytic Upgrading of Biomass-Gasification Mixtures Using Ni-Fe/ MgAl2O4 as a Bifunctional Catalyst
Tarifa, P; Reina, TR; González-Castaño, M; Arellano-Garcia, HEnergy & Fuels, 36 (2022) 8267-8273 DOI: 10.1021/acs.energyfuels.2c01452

Abstract
Biomass gasification streams typically contain a mixture of CO, H-2, CH4, and CO(2 )as the majority components and frequently require conditioning for downstream processes. Herein, we investigate the catalytic upgrading of surrogate biomass gasifiers through the generation of syngas. Seeking a bifunctional system capable of converting CO2 and CH4 to CO, a reverse water gas shift (RWGS) catalyst based on Fe/MgAl(2)O(4 )was decorated with an increasing content of Ni metal and evaluated for producing syngas using different feedstock compositions. This approach proved efficient for gas upgrading, and the incorporation of adequate Ni content increased the CO content by promoting the RWGS and dry reforming of methane (DRM) reactions. The larger CO productivity attained at high temperatures was intimately associated with the generation of FeNi3 alloys. Among the catalysts' series, Ni-rich catalysts favored the CO productivity in the presence of CH4, but important carbon deposition processes were noticed. On the contrary, 2Ni-Fe/MgAl2O4 resulted in a competitive and cost-effective system delivering large amounts of CO with almost no coke deposits. Overall, the incorporation of a suitable realistic application for valorization of variable composition of biomass-gasification derived mixtures obtaining a syngas-rich stream thus opens new routes for biosyngas production and upgrading.
August, 2022 · DOI: 10.1021/acs.energyfuels.2c01452
Química de Superficies y Catálisis
Catalytic reforming of model biomass-derived producer gas
Azancot, L; Bobadilla, LF; Centeno, MA; Odriozola, JAFuel, 320 (2022) 123843 DOI: 10.1016/j.fuel.2022.123843

Abstract
This work includes a complete study of the reaction of reforming a simulated producer gas stream comparing a Ni-based catalyst with another one promoted with potassium to enhance the resistance to coke formation. Although coke deposition is unavoidable in the presence of tars in the stream, the analysis of different reaction parameters revealed that operating at 750 degrees C, weight hourly space velocity (WHSV) of 60 L-1 g(-1) h(-1) and 10-20 vol% of steam is possible to minimize the accumulation of carbon deposits. Moreover, it was demonstrated that the addition of potassium helps to mitigate carbon formation, but a high concentration of steam leads to nickel sintering and/or partial oxidation of metallic nickel. On this basis, it was successfully evidenced that the Ni-K catalyst is an excellent candidate for obtaining clean syngas from producer gas reforming.
July, 2022 · DOI: 10.1016/j.fuel.2022.123843
Materiales de Diseño para la Energía y Medioambiente
Flame confinement in biomass combustion systems for particles abatement
Ciria, D; Orihuela, MP; Moreno-Naranjo, P; Chacartegui, R; Ramirez-Rico, J; Becerra, JAEnergy Conversion and Management, 264 (2022) 115706 DOI: 10.1016/j.enconman.2022.115706
Abstract
This work explores the use of open-pore, inert ceramic foams with different pore sizes as particle abatement systems in small biomass combustion systems. Porous foams made of silicon carbide with pore sizes 10 to 60 pores-per-inch were installed in an in-house designed combustion unit operated with wood pellets. Their effects on the temperature distribution inside the chamber, particulate and gases emissions were studied using different airflow rates in the reaction-limited regime (low equivalence ratio) to minimise stoichiometric factors. The influence of pore size, foam position with respect to the flame and space velocity were assessed. The confinement of the flame with inert foams was found to substantially modify the temperature distribution in the combustion chamber, improve the air-fuel mixture, and favour the thermal decomposition of the pellet, leading to a reduction in particulate emissions when compared to free-flame combustion at the same experimental conditions. In general, the amount of particulate matter was found to decrease by up to one order of magnitude as the pore size of the foam was reduced, while the temperature gradient in the combustion chamber was increased. Nitrogen oxides and carbon dioxide emissions were essentially unchanged, irrespectively of the pore size of the foam. It is expected that these values will be improved with longer residence times, as happens in operations with reduced excess air ratios. These results suggest that it is possible to control pollutants derived from domestic heating within the most restrictive current regulations on particulate emissions by integrating flame confinement designs with better operating practices and efficient abatement systems.
July, 2022 · DOI: 10.1016/j.enconman.2022.115706
Reactividad de Sólidos
Albero: An alternative natural material for solar energy storage by the calcium-looping process
Moreno, V; Arcenegui-Troya, J; Sanchez-Jimenez, P; Perejon, A; Chacartegui, R; Valverde, JM; Perez-Maqueda, LAChemical Engineering Journal, 440 (2022) 135707 DOI: 10.1016/j.cej.2022.135707

Abstract
Large-scale thermochemical energy storage (TCES) is gaining relevance as an alternative to current thermal energy storage systems in Concentrated Solar Power plants. Among the different systems, the reversible reaction between CaO and CO2 stands out due to the wide availability and low cost of the raw material: limestone. Direct solar absorption of the storage media would improve the efficiency of solar-to-thermal energy storage due to reduced thermal transfer barriers, but the solar optical absorption of CaCO3 is poor. In this work, we propose the use of a Ca-rich calcarenite sedimentary rock so-called albem as an alternative to limestone. We demonstrate that this reddish material exhibits an average solar absorptance that is approximately ten times larger than limestone. Moreover, the multicycle carbonation/calcination performance under different experimental conditions has been studied by thermogravimetry, and similar values to those exhibited for limestone have been obtained. Besides, the material is cheap (6 Elton), and simulations showed that the use of this material would significantly improve the overall CaL-CSP efficiency at the industrial level.
July, 2022 · DOI: 10.1016/j.cej.2022.135707
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