Scientific Papers in SCI

Abstract

The study explored the incorporation of Cu into Mg2Al1 hydrotalcite-like layered double hydroxides (LDH) and their derived mixed oxides for efficient methyl orange (MO) adsorption. MgAl -LDH (MA -LDH), MgCuAl - LDH(MCA - LDH), and their 500 degrees C thermally treated derivatives (MA - O and MCA-O) were successfully synthesized and comprehensively characterized. Copper doping notably enhanced the adsorption capacity by improving the textural properties and facilitating the formation of a more abundant MgAl2O4 spinel phase in the mixed oxide. The decomposition of both raw and modified LDHs promoted strong interactions with MO, overcoming the mass transfer limitations typically associated with diffusion. The pseudo-second-order (PSO) kinetic model was found to best describe the adsorption behavior of the mixed oxides. The effects of solid-liquid ratio and pH, along with response surface methodology (RSM) using a Box-Behnken design (BBD), were investigated to optimize the adsorption conditions of MO on the MCA -O mixed oxide. Equilibrium and thermodynamic studies revealed a high adsorption capacity for MO (qmax = 1297mg/g at 25 degrees C), with adsorption being both spontaneous and endothermic. Langmuir isotherm and advanced statistical modeling indicated that MO molecules adsorbed on MCA -O formed a monolayer with a general lateral arrangement. Post-adsorption characterization and DFT calculations were employed to gain deeper insight into the adsorption mechanism, which was primarily driven by ion exchange, hydrogen bonding, and pi - pi complexation. The mixed oxide derived from LDH demonstrated excellent stability and remained effective over multiple cycles without significant performance loss.

Abstract

In this paper, visible light-activated phosphorus-doped TiO2 (P-TiO2) was used as a photoactive phase to prepare polymer composites for the degradation of the pesticide thiacloprid under direct sunlight irradiation. In particular, a monolithic composite aerogel, consisting of P-TiO2 embedded in syndiotactic polystyrene (PTsPS), and a composite polymer film, consisting of P-TiO2 immobilized on the surface of a Corona-pretreated polypropylene film (PT/PP), were prepared and characterized by XPS, TEM, XRD and N2 adsorption at-196 degrees C. The latter were then tested for the degradation of thiacloprid under solar irradiation. The best results were obtained using the PT/PP composite film, which allowed the total degradation of thiacloprid after 180 min of treatment. This performance remained almost unchanged even after several reuse cycles. The effect of pH and the concentration of bicarbonate (HCO3-), calcium (Ca2+), and chloride (Cl-) ions on the PT/PP film photocatalytic activity was also investigated. In addition, the photocatalytic activity of the PT/PP film remained high even in the presence of drinking water spiked with the target pollutant. Photocatalytic tests in the presence of scavenger molecules clarified that the hydroxyl radical is the main reactive oxygen species (ROS) responsible for the photodegradation mechanism of the target pollutant with P-TiO2, even if a possible role of superoxide cannot be excluded. Finally, DFT studies and ESI(+)-FT-ICR-MS analysis were conducted to formulate a hypothesis on the degradation pathway, identifying possible reaction intermediates.

Abstract

This study investigates biomass-derived adsorbents in powder and bead forms for the efficient removal of methylene blue MB from wastewater. Activated biochar powders (ABC and ABCZ) were synthesized using H3PO4 and ZnCl2 as activators for the chemical treatment of Crataegus azarolus CAS seed waste, while polyaniline (PA) and sodium alginate (SG) were integrated to form two bead-shaped composites. Compared to ZnCl2, H3PO4 activation produced similar acidic site concentrations but resulted in improved mesoporosity and larger pore diameters. Untreated lignin-like ABC and PA-functionalized ABC were successfully encapsulated into uniform composite beads (ABC-SG and ABC-PA-SG) with negatively charged surfaces at neutral pH of solution as confirmed by FTIR, TGA, and pHpzc analyses. Adsorption efficiency depended on material composition, form, and texture. Encapsulation significantly enhanced MB adsorption capacity, with ABC-PA-SG beads achieving 821 mg/g, compared to 261 mg/g for ABC powder. While greater surface area improved MB adsorption in powders, PA incorporation in composite beads contributed to higher adsorption performance. Kinetic modeling showed that MB adsorption on ABC powder was governed by chemisorption and pores filling, while composite beads followed a physical interaction-driven process. Thermodynamic analysis confirmed that adsorption was spontaneous and endothermic. Statistical modeling and DFT calculations provided deeper insights into the adsorption mechanisms. it-it interactions dominated MB adsorption, with a horizontal molecular arrangement. ABC powders exhibited multi- layer pore filling on a heterogeneous surface, whereas adsorption on ABC-PA-SG beads followed a double-energy double-layer mechanism. This study provides integrated insights into biomass-derived composite beads adsorbents, highlighting their potential for sustainable wastewater treatment applications.

Abstract

Plasticized cellulose bioplastics with antioxidant and antimicrobial properties were prepared by blending cellulose and glycerol in a mixture of trifluoroacetic acid and trifluoroacetic anhydride, adding a solution of beeswax in chloroform, and subsequent drop-casting. Optical, chemical, structural, mechanical, thermal, and hydrodynamic properties were fully characterized. In addition, the biodegradability in seawater was investigated by determination of the biological oxygen demand. The incorporation of beeswax ruled out the transparency and UV blocking, modified the main mechanical parameters, and improved the thermal stability and the antioxidant capacity, as well as the hydrodynamic and barrier properties. In general, these features were comparable to those of common petroleum-based food packaging plastics. Such changes were explained by the incorporation of beeswax into the polymer matrix, as determined by infrared spectroscopy and X-ray diffraction. These cellulosebeeswax bioplastics were evaluated as viable food packaging materials by determination of the overall migration by using Tenax (R) as a dry food simulant, oxygen permeability at different relative humidities, measurement of antimicrobial activity against Escherichia coli and Bacillus cereus, and through preservation of fresh-cut pear slices, showing results similar to those obtained by using low-density polyethylene.

Abstract

Access to clean water is crucial for human health, yet microbial contamination poses significant challenges. This study investigates the effectiveness of novel photocatalytic catalysts: heterostructured TiO₂/AgBr and faceted titanium dioxide, for microbial inactivation under ultraviolet and visible light. Both catalysts were synthesized and characterized. Performance was evaluated using real wastewater samples and saline solutions, targeting gram-positive and gram-negative bacteria. The experimental approach included testing the photocatalysts with and without the addition of peroxydisulfate to assess its impact on inactivation effectiveness. Results indicated that the TiO₂/AgBr catalyst outperformed the faceted titanium dioxide one due to its superior visible light absorption and enhanced charge separation, achieving complete inactivation of environmental strains of Escherichia coli and significant inactivation for Enterococcus faecalis in real wastewater. The inclusion of peroxodisulfate with TiO₂/AgBr significantly improved inactivation rates, demonstrating a synergistic effect. Regarding wastewater composition, the treatment achieves a significant COD removal while the rest of studied parameters remain stable. Both catalysts effectively prevented bacterial regrowth for up to 48 hours, underscoring its long-term efficacy. Overall, these findings highlight the potential application of TiO₂/AgBr combined with peroxodisulfate as an effective strategy for microbial inactivation, contributing to the advancement in water treatment technologies across real environmental contexts.

Abstract

Exploring synergistic interactions between nanomaterials that can enhance their collective properties in ways that individual components cannot achieve represents an avenue for advancing beyond the current state of the art. This approach is particularly relevant in the context of ABX(3) nanocrystals, where pursuing cooperation could help to overcome current challenges associated with light generation. Transparent photoluminescent coatings are developed by combining perovskite nanomaterials and porous scaffolds of high optical quality phosphor nanoparticles. Fine tuning of the spectral content of the emission is achieved with the photoexcitation wavelength, allowing the demonstration of white light emission with tunable hues.

Abstract

This article presents a reproducible and affordable methodology for fabricating organic nanowires (ONWs) and nanotrees (ONTs) as light-enhanced conductometric O2 sensors. This protocol is based on a solventless procedure for the formation of high-density arrays of nanowires and nanotrees on interdigitated electrodes. The synthesis combines physical vapour deposition for the self-assembled growth of free-phthalocyanine nanowires and soft plasma etching to prompt the nucleation sites on the as-grown ONWs to allow for the formation of nanotrees. Electrical conductivity in such low-dimensional electrodes was analysed in the context of density, length, and interconnection between nanowires and nanotrees. Furthermore, the electrodes were immersed in water to improve the nanowires' connectivity. The response of the nanotrees as conductometric O2 sensors was tested at different temperatures (from room temperature to 100 degrees C), demonstrating that the higher surface area exposed by the nanotrees, in comparison with that of their polycrystalline thin film counterparts, effectively enhances the doping effect of oxygen and increases the response of the ONT-based sensor. Both organic nanowires and nanotrees were used as model systems to study the augmented response of the sensors provided by illumination with white or monochromatic light to organic semiconducting systems. Interestingly, the otherwise negligible sensor response at room temperature can be activated (On/Off) under LED illumination, and no dependency on the illumination wavelength in the visible range was observed. Thus, under low-power LED illumination with white light, we show a response to O2 of 16% and 37% in resistivity for organic nanotrees at room temperature and 100 degrees C, respectively. These results open the path to developing room temperature long-lasting gas sensors based on one- and three-dimensional single-crystalline small-molecule nanowires.

Abstract

Direct upgrading of biogas by CO2 methanation aims to produce a gas to be injected into the grid. Operating at moderate pressures favors thermodynamics, but catalyst surface and reaction mechanism under realistic conditions are not well investigated. We study the role of basic and metallic sites on performance and mechanism of clean biogas methanation (CO2/CH4=1/1 v/v) at 1, 5 and 7 bar. Ni/Mg/La/Al hydrotalcite-derived catalysts, with different Ni and La contents, are investigated combining tests and physico-chemical characterization, including quasi-in situ XPS at 7 bar, with CO2-adsorption and methanation DRIFTS at 1 and 7 bar, respectively. An optimized catalyst (6.5 wt% La, 35 wt% Ni) with 3-4 nm Ni0 and balanced basicity, achieves 96 LCH4*gcat- 1* h- 1 (300 degrees C, 7 bar). DRIFTS confirm catalysts activity experimental trend. Optimizing Ni and La results in higher consumption rates of formate intermediate and sufficient Ni0 sites for CO formation. Increasing pressure to 7 bar promotes CO and m-HCOO reactivity.

Abstract

CO₂ hydrogenation with green hydrogen is a practical approach for the reduction of CO₂ emissions and the generation of high-value-added chemicals. Generally, product selectivity is affected by the associated reaction mechanisms, internal catalyst identity and structure, and external reaction conditions. Here we examine typical CO₂ hydrogenation reaction pathways, which can provide insight useful for the atomic-level design of catalysts. We discuss how catalyst chemical states, particle sizes, crystal facets, synergistic effects and unique structures can tune product selectivity. Different catalysts, such as Fe-, Co-, Ni-, Cu-, Ru-, Rh-, Pd-based and bifunctional structured catalysts, and their influence on CO₂ hydrogenation products (such as CO, methane, methanol, ethanol and light olefins) are discussed. Beyond catalyst design, emerging catalytic reaction engineering methods for assisting the tuning of product selectivity are also discussed. Future challenges and perspectives in this field are explored to inspire the design of next-generation selective CO₂ hydrogenation processes to facilitate the transition towards carbon neutrality.

Abstract

Research on the reutilization of crop residues has gained significant attention as a strategy for generating energy and high-value chemicals from renewable sources, while simultaneously reducing feedstock costs and mitigating environmental pollution. Crop residues have been effectively applied in lignocellulosic sulfate-reducing bioreactors (LSRBs) for the treatment of mining-influenced water. A comprehensive evaluation of the state-of-the-art in LSRBs reveals their potential for leveraging syntrophic aerobic-anaerobic interactions between sulfate-reducing bacteria and facultative species, alongside cellulolytic-fermentative microorganisms, to facilitate the pretreatment of lignocellulosic biomass for biorefinery applications. Key variables influencing the availability of enzymatic substrates and the activity of lignin-degrading enzymes are identified, along with strategies to enhance catalytic efficiency. Additionally, approaches to ensure the availability of trace elements and to control the production of toxic intermediates that may hinder treatment processes are elucidated. Prominent strategies include the application of microaeration and the use of co-substrates. An innovative aspect is the exploitation of metal sulfide precipitation to mitigate toxicity while preventing the sequestration of hydrogen peroxide - an essential substrate for enzymatic activity - by sulfides generated during the process. This review emphasizes the need for scientific advancements focused on optimizing the valorization of lignocellulosic residues. A particular focus is placed on advancing the understanding of lignin's anaerobic degradation mechanisms, especially in systems co-treating lignocellulosic waste and mining-influenced waters. Such advancements hold promise for enhancing the efficiency and sustainability of biorefinery operations.

Abstract

A joint theory-experimental study is presented of irregularly shaped nano-pores in amorphous silicon. STEM- ELLS spectra were measured for each pore. The observed helium 1 s 2- 1 s 2 p( 1 P ) excitation energies were found to be shifted from that of a free atom. The relation between the helium density in the pore and these energy shifts is explored and shown to be completely consistent with earlier studies of helium in its bulk condensed phases as well as encapsulated as bubbles in solid silicon. The density, pressure and depth of the pores, all key properties for applications, were determined. An alternative and novel method for determining the depth of the pores more accurately is presented.

Abstract

The first demonstration of plasma-flash sintering (PFS) is presented in this work. PFS is performed under a low-pressure atmosphere that consecutively generates plasma and flash events. It is shown, by using several combined characterization techniques, that PFS stabilizes metastable phases on the surface of the material, which may be partially, but not solely, attributed to the generation of oxygen vacancies, and induces the absorption of ionized species, if a reactive atmosphere is employed. Even though additional research is required to understand the fundamentals of PFS, it is evidenced its potential to be used as a material surface engineering tool, which may widen the technological capabilities of flash sintering.

Cover Photograph: Plasma-Flash Sintering (PFS) is performed under low-pressure atmosphere that consecutively generates plasma and flash events. This study shows that PFS stabilizes metastable phases on the surface of the material and enables absorption of ionized species generated in the plasma, giving this technique potential to be used as a surface engineering tool. Read more in the rapid communication in this issue,

Abstract

Metal-Organic frameworks (MOFs) are promising candidates for advanced photocatalytically active materials. These porous crystalline compounds have large active surface areas and structural tunability and are thus highly competitive with oxides, the well-established material class for photocatalysis. However, due to their complex organic and coordination chemistry composition, photophysical mechanisms involved in the photocatalytic processes in MOFs are still not well understood. Employing electron paramagnetic resonance (EPR) spectroscopy and time-resolved photoluminescence spectroscopy (trPL), the fundamental processes of electron and hole generation are investigated, as well as capture events that lead to the formation of various radical species in UiO-66, an archetypical MOF photocatalyst. A manifold of photoinduced electron spin centers is detected, which is subsequently analyzed and identified with the help of density-functional theory (DFT) calculations. Under UV illumination, the symmetry, g-tensors, and lifetimes of three distinct contributions are revealed: a surface O2-radical, a light-induced electron-hole pair, and a triplet exciton. Notably, the latter is found to emit (delayed) fluorescence. The findings provide new insights into the photoinduced charge transfer processes, which are the basis of photocatalytic activity in UiO-66. This sets the stage for further studies on photogenerated spin centers in this and similar MOF materials.

Abstract

One of the biggest players in the world economy is the naval industry, which mainly controls the merchandise transportation sector. Any issue with ships could represent millions of USD of loss and increases in the cost of goods for the population worldwide. Two main problems which this industry has fought are corrosion and biofouling. Lastly, the pollution of the sea has gained importance, and more strict policies have been applied regarding the use of certain products by this industry. One of these is paintings, which represented this industry's definitive solution to avoid the mentioned problems for a long time. This situation allowed to explore other solutions like PVD coatings through multifunctional coatings. Zirconium nitride has been demonstrated to be useful in resisting corrosion with reliable mechanical properties. However, this material does not possess antimicrobial action. The present study presents a nanostructured coating combining ZrN with Cu, which works as a biocide, contributing to the desired multifunctionality. The developed coating was obtained using a hybrid magnetron co-sputtering employing High-power impulse (HiPIMS) and direct current (DCMS) power sources under a reactive atmosphere. SEM, EDX, XRD and Raman spectroscopy were used to assess the physico-chemical properties of the coatings. Besides, depth-sensing nano-indentation explored the mechanical properties. The tribological performance was tested by a reciprocating tribometer under dry and wet (with 3.5 % w/w NaCl solution) contact conditions and employing a soda lime glass ball as a counterbody. The results showed that adding Cu to ZrN through this technology resulted in a limited hardness reduction from 19 (pure ZrN) to 14 GPa. Also, the chemical activation with NaOCl solution softens the obtained coating and, together with the saline solution, influences the wear resistance. However, the nanostructured coating has been demonstrated to be suitable for use under real conditions, without loss of its protection over the used substrate. It opens a new possibility of a solution for the naval industry.

Abstract

This study presents the photocatalytic degradation of the aminophosphonate ethylenediaminetetra(methylenephosphonic acid) (EDTMP) with a range of different doped nanoparticles (NP). The photocatalysts were based on TiO2 benchmark P25 and gold (Au) doped either with sodium (Na), potassium (K) or yttrium (Y). The synthesized photocatalysts were characterized via TEM, XRF, XRD, UV-DRS (band gap estimation) and N2-phys- isorption. Photocatalytic pre-screening at pH values of 3, 7 and 10 indicated highest o-PO4 release of EDTMP at pH 7 and 10 for NP either doped with K or Y. The results of LC/MS analysis showed that the NPs doped with 5 % Y (Au2/Y5/P25) resulted in the fastest degradation of EDTMP. The target compound was completely degraded within 60 min, 4 times faster than photochemical treatment of unadulterated EDTMP. Importantly, also the transformation products were accelerated by the photocatalytic treatment with Au2/P25 either doped with 5 % Y or 10 % K. The results of scavenger experiments indicated that the enhanced photocatalytic degradation of EDTMP is primarily attributable to the presence of hydroxyl radicals in the bulk and to a lesser extent to center dot O2- and electron-holes (h+) at the surface of the catalysts. The study demonstrates that the catalytic efficiency of TiO2 nanocomposites is significantly influenced by the choice of dopants, which affect particle size, band gap, and photocatalytic activity. Yttrium at low concentrations (i.e., 5 wt% Y) doping emerged as particularly effective, enhancing both the visible light absorption and h+ separation, leading to superior photocatalytic performance in the degradation of EDTMP. The Au content also plays a crucial role in enhancing the photocatalytic efficiency. However, the combination of Au and Na doping was found to be less effective for this photocatalysis in aqueous media, potentially due to larger particle sizes and insufficient dopant contents. In conclusion, the findings emphasise the necessity of optimising both the selection of dopants and the design of catalysts in order to enhance photocatalytic applications.

Abstract

Ethylene, as an important chemical raw material, could be produced through the coal-based acetylene hydrogenation route. Nickel-based catalysts demonstrate significant activity in the semihydrogenation reaction of acetylene, but they encounter challenges related to catalyst deactivation and overhydrogenation. Herein, the effect of Sn promoter on Ni/CeO2 catalysts has been comprehensively explored for acetylene semihydrogenation. The optimized Ni/8%Sn-CeO2 catalytic performance was significantly improved, with 100% acetylene conversion and 82.5% ethylene selectivity at 250 degrees C, and the catalyst maintained high catalyst performance within a 1000 min stability test. A series of characterization tests show that CeO2 modified by moderate Sn4+ doping is more conducive to modulating the charge structure and geometry of the Ni active center. Additionally, the in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy and density functional theory results indicated that catalysts doped with Sn4+ facilitated more efficient desorption of ethylene from the catalyst surface compared to Ni/CeO2 catalysts, thus improving ethylene selectivity and yield. This study highlights an effective strategy for improving the catalytic performance of rare-earth-based catalysts through the incorporation of effective metal promoters.

Abstract

Poly(vinylidene fluoride) (PVDF) is a piezoelectric and thermoplastic material with great potential for additive manufacturing (AM) applications. Using barium titanate (BaTiO₃) as filler, PVDF-based composite materials were developed, characterized, and processed by AM material extrusion (MEX). The morphological features and phase transformations occurring throughout the processing of BaTiO₃-filled PVDF, from the compounding to the printed part, were analyzed. The morphology of the powder feedstock after dispersion in a high-energy ball mill changed from spheroidal to laminar and β-phase formation was favored. Microhardness gradually increased with the BaTiO₃ content, obtaining an enhancement of ~60% for a content of 25 vol%, and supported the good dispersion of the filler. A ~48% increase of the dielectric permittivity was also achieved. After extrusion, filaments with a filler content of 15 vol% showed a more stable diameter, as well as higher crystallinity and surface roughness, compared with those with lower BaTiO₃ contents. Material extrusion of filament and direct printing of pellets based on MEX were successfully used to obtain AM parts. Composite parts showed enhanced surface roughness, hydrophilicity, and flexural modulus (up to ~33% for the 7 vol% composite compared with the PVDF), thus leading to superior mechanical characteristics and potential biomedical applications.

Abstract

La2Mo2O9 is acknowledged as an exceptional oxide ion conductor. It undergoes a reversible phase transition around 580 degrees C from the nonconductive low-temperature monoclinic alpha-La2Mo2O9 phase to the highly conductive high-temperature cubic beta-La2Mo2O9 phase. In addition, La2Mo2O9 demonstrates complex chemistry under reducing conditions. This study reports, for the first time, the stabilization at ambient temperature of a novel cubic phase through a topotactic reduction of alpha-La2Mo2O9 employing CaH2. This phase contains approximately similar to 3 atom % oxygen vacancies relative to the nominal composition (La2Mo2O8.68(1)). The cubic symmetry is associated with a static distribution of these vacancies, in contrast to the dynamic distribution observed in the high-temperature cubic beta-La2Mo2O9 phase reported previously. Additionally, the material exhibits mixed-ion-electronic conduction, which expands its potential use in applications requiring both ionic and electronic transport.

Abstract

Active and sustainable food packaging materials were prepared through solvent casting, by blending tea waste (TW) extract rich in bioactive molecules with a neat polylactide (PLA) polymeric matrix. The optimization of tea waste extraction using a response surface methodology allowed achieving efficient yield and high phenolic content, which significantly enhanced the antioxidant properties of the resulting bioplastics. TW extract incorporation into PLA films increased UV-blocking capability, while keeping the oxygen permeability performance. Mechanical testing revealed improved ductility and toughness in TW extract-containing films compared to pure polylactide film, ascribed to the plasticizing effect of TW polyphenols. Food packaging assays showed effective moisture retention, comparable to low-density polyethylene (LDPE) plastics, antioxidant activity, and excellent bacteria barrier properties allowing the use for food packaging applications. Moreover, migration tests and detection of non-intentionally added substances (NIAS) allowed to establish the safety and regulatory compliance of these bioplastics.

Abstract

Microplastics fibers shed from washing synthetic textiles are released directly into the waters and make up 35% of primary microplastics discharged to the aquatic environment. While filtration devices and regulations are in development, safe disposal methods remain absent. Herein, we investigate catalytic hydrothermal carbonization (HTC) as a means of integrating this waste (0.28 million tons of microfibers per year) into the circular economy by catalytic upcycling to carbon nanomaterials. Herein, we show that cotton and polyester can be converted to filamentous solid carbon nanostructures using a Fe-Ni catalyst during HTC. Results revealed the conversion of microfibers into amorphous and graphitic carbon structures, including carbon nano- tubes from a cotton/polyethylene terephthalate (PET) mixture. HTC at 200 degrees C and 22 bar pressure produced graphitic carbon in all samples, demonstrating that mixed microfiber wastes can be valorized to provide potentially valuable carbon structures by modifying reaction parameters and catalyst formulation.

Abstract

Doped-PrBaMn2-xTMxO5+delta samples with TM = Co and/or Ni were synthesized by a mechanochemical route from stoichiometric oxide precursor mixtures (Pr6O11, BaO2, MnO, NiO and CoO) using a planetary mill at 600 rpm for 150 min. A disordered ABO(3) pseudocubic perovskite phase was obtained after the milling process that was transformed, as established by XRD, into the double layered AA'B2O5+delta perovskite phase after annealing at 900 degrees C in a reducing atmosphere (10%H-2/Ar). The microstructural characterization by SEM, TEM, and HRTEM ascertained that this reducing treatment induced the exsolution of Ni and Co metallic nanoparticles from the doped samples. Ni-Co alloys were even exsolved when the layered manganite phase was co-doped with both transition metals. It was confirmed that the exsolution process was reversible by switching the working atmosphere from reducing to oxidizing. Polarization resistance values of the doped samples determined in symmetrical cells in air and H-2, as well as the electrochemical performance of electrolyte LSGM-supported planar cells suggested that these samples can be used as symmetrical electrodes in SOFCs.

Abstract

This article discusses the 'power-to-X' (P2X) concept, highlighting the integral role of non-thermal plasma (NTP) in P2X for the eco-friendly production of chemicals and valuable fuels. NTP with unique thermally non-equilibrium characteristics, enables exotic reactions to occur under ambient conditions. This review summarizes the plasma-based P2X systems, including plasma discharges, reactor configurations, catalytic or non-catalytic processes, and modeling techniques. Especially, the potential of NTP to directly convert stable molecules including CO2, CH4 and air/N2 is critically examined. Additionally, we further present and discuss hybrid technologies that integrate NTP with photocatalysis, electrocatalysis, and biocatalysis, broadening its applications in P2X. It concludes by identifying key challenges, such as high energy consumption, and calls for the outlook in plasma catalysis and complex reaction systems to generate valuable products efficiently and sustainably, and achieve the industrial viability of the proposed plasma P2X strategy.

Abstract

The development of highly efficient and selective catalysts for carbonylation reactions represents a significant challenge in catalysis. Single-atom catalysts (SACs) have postulated as promising candidates able to combine the strengths of both homogeneous and heterogeneous catalysts. In this paper, we review recent advances in tailoring solid supports for SACs to enhance their catalytic performance in carbonylation reactions. We first discuss the effect of supports on the hydroformylation reaction catalysed by SACs, followed by recent advances for methanol, ethanol, and dimethyl ether carbonylation reactions, focusing on the design of halide-free catalysts with improved activity and stability. Finally, oxidative carbonylation is discussed. Overall, this review highlights the importance of tailoring solid supports for SACs to achieve highly active and selective catalysts in carbonylation reactions, paving the way for future developments in sustainable catalysis.

Abstract

Lead halide perovskite nanocrystals are attractive for light emitting devices both as electroluminescent and color-converting materials since they combine intense and narrow emissions with good charge injection and transport properties. However, while most perovskite nanocrystals shine at green and red wavelengths, the observation of intense and stable blue emission still remains a challenging target. In this work, a method is reported to attain intense and enduring blue emission (470–480 nm), with a photoluminescence quantum yield (PLQY) of 40%, originating from very small CsPbBr₃ nanocrystals (diameter < 3 nm) formed by controllably exposing Cs₄PbBr₆ to humidity. This process is mediated by the void network of a mesoporous transparent scaffold in which the zero-dimensional Cs₄PbBr₆ lattice is embedded, which allows the fine control over water adsorption and condensation that determines the optimization of the synthetic procedure and, eventually, the nanocrystal size. The approach provides a means to attain highly efficient transparent and stable blue light-emitting films that complete the palette offered by perovskite nanocrystals for lighting and display

Abstract

Herein, it is reported the concomitant synthesis and sintering in a single step of (Mn0.2Co0.2Ni0.2Cu0.2X0.2)Fe2O4 (X=Fe, Mg), a spinel-structured high-entropy oxides, by the reactive flash sintering technique. A single phase, identified with a spinel crystal structure Fd3m, was obtained in just 30 min at a furnace temperature of 1173 K. The structural and magnetic properties of the prepared compounds were assessed by the combined use of various techniques, aiming to understand the correlations between functional properties and crystal structure. Characteristic features of the Mossbauer spectra prove the existence of different nonequivalent Fe environments . Both compositions display soft magnetic behavior, characterized by low coercive fields and saturation magnetization reached at low fields. Thus, the substitution of nonmagnetic Mg2+ for magnetic Fe2+ results in a decrease in magnetic parameters due to the weakening of the super-exchange interaction among the magnetic moments.

Abstract

VOx/TiO₂ catalysts with various theorical monolayer values have been prepared and used to study, for the first time, the effect of vanadium loading in the selective oxidation of glucose to formic acid. Monomeric or isolated vanadia species dominate at low loadings, evolving into polymeric chains at higher concentrations, while crystalline V₂O₅ is observed at loadings over the theoretical monolayer value. Their characterization by XRD, BET, ICP, DRIFTS, Raman, UV–vis, H₂-TPR and NH₃-TPD reveal distinct physicochemical characteristics influenced by the formed vanadia species, impacting sample acidity, reducibility, and catalytic activity. All catalysts exhibit significant activity, forming formic acid as the main product in the liquid phase and reaching a peak formic acid yield of 42 %. Post-reaction analysis reveals that the leaching-prone crystalline V₂O₅ compromises catalyst stability while isolated vanadia species demonstrate superior catalytic activity and leaching resistance. The findings of this study provide a strong basis for the development of a heterogeneous vanadia catalyst with improved interaction with the support.

Abstract

Two series of open metal site MOFs, HKUST-1 and MIL-100(Fe), have been successfully prepared using different methods of synthesis. Their features depend on the synthetic route as well as their role play in different environmental applications. The stability and performance of these BTC-based MOFs have been tested bearing in mind Congo Red (CR) removal, humidity adsorption and iodine capture and release. HKUST-1 and MIL-100(Fe) samples could offer a remarkable role in the adsorption of CR from aqueous solutions. However, the lability of HKUST-1 in water is revealed as a drawback for its reutilization in both static and agitation conditions. The former contrasts to the stability under ambient moisture. MIL-100(Fe) shows promising properties in both CR adsorption in aqueous solutions and humidity adsorption. Nonetheless, the performance largely depends on the synthesis conditions. Although CR removal is based on surface interaction, there is a relation between the adsorpted quantity and the specific surface area. The size and nature of iodine allows the diffusion in the pores of both HKUST-1 and MIL-100(Fe) MOFs. This way, the uptake of iodine is driving by the porosity and surface area of samples rather than their inherent nature. As a rule, the results of this work indicate that not only is it important the specific nature of the MOF chosen for a given application but also the way in which it has been synthesized and the conditions in which they are used. MIL-100(Fe)-R is revealed as the best suitable candidate to be used as a sorbent for CR in aqueous solutions, moisture and I2 gas.

Abstract

Kinetic models are relevant to describe heterogeneous kinetic processes; a number of kinetic models and their mathematical expressions have been reported in the literature, many of these based on idealistic conditions in terms of geometrical constrain and driving forces. Alternatively, the semi-empirical Sestak-Berggren (SB) conversion function, which was proposed as a general equation, encompasses a large variety of equations corresponding to different kinetic models. Despite the fact that the SB equation does not provide any physical meaning, it is extremely useful for kinetic analysis as it offers a good fit to experimental data even when they do not follow the ideal conditions assumed for the conventional kinetic models. One limitation of the SB kinetic model is the fact that its conversion function cannot be analytically integrated to provide an exact solution; thus, it cannot be directly applied in kinetic integral methods. The objective of this study aims to propose some solutions for some specific cases, while the mathematical limits for the values of the kinetic exponents m, n, p of the SB model and their validity are also explored. Further ideas for improving the SB equation or finding an alternative for a superior conversion function were explored in this work.