Scientific Papers in SCI
2016
2016
Materiales de Diseño para la Energía y Medioambiente
Biodegradable polyester films from renewable aleuritic acid: surface modifications induced by melt-polycondensation in air
Benitez, JJ; Heredia-Guerrero, JA; de Vargas-Parody, MI; Cruz-Carrillo, MA; Morales-Florez, V; de la Rosa-Fox, N; Heredia, AJournal of Physics D-Applied Physics, 49 (2016) 175601 DOI: 10.1088/0022-3727/49/17/175601
Abstract
Good water barrier properties and biocompatibility of long-chain biopolyesters like cutin and suberin have inspired the design of synthetic mimetic materials. Most of these biopolymers are made from esterified mid-chain functionalized.-long chain hydroxyacids. Aleuritic (9,10,16-trihydroxypalmitic) acid is such a polyhydroxylated fatty acid and is also the major constituent of natural lac resin, a relatively abundant and renewable resource. Insoluble and thermostable films have been prepared from aleuritic acid by melt-condensation polymerization in air without catalysts, an easy and attractive procedure for large scale production. Intended to be used as a protective coating, the barrier's performance is expected to be conditioned by physical and chemical modifications induced by oxygen on the air-exposed side. Hence, the chemical composition, texture, mechanical behavior, hydrophobicity, chemical resistance and biodegradation of the film surface have been studied by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), nanoindentation and water contact angle (WCA). It has been demonstrated that the occurrence of side oxidation reactions conditions the surface physical and chemical properties of these polyhydroxyester films. Additionally, the addition of palmitic acid to reduce the presence of hydrophilic free hydroxyl groups was found to have a strong influence on these parameters.
May, 2016 · DOI: 10.1088/0022-3727/49/17/175601
Reactividad de Sólidos
Hot-pressing of (Ti,Mt)(C,N)-Co-Mo2C (Mt = Ta,Nb) powdered cermets synthesized by a mechanically induced self-sustaining reaction
Chicardi, E; Gotor, FJ; Medri, V; Guicciardi, S; Lascano, S; Cordoba, JMChemical Engineering Journal, 292 (2016) 51-61 DOI: 10.1021/acsami.6b00232

Abstract
A mechanically induced self-sustaining reaction (MSR) has been successfully employed for manufacturing powdered cermets based on Ti, Ti–Ta and Ti–Nb carbonitrides using Co as the binder phase and Mo2C as the sintering additive. The powders were sintered by hot-pressing, and complete chemical, microstructural and mechanical characterizations were performed on the densified cermets. When elemental Ta, Nb and/or Mo2C were added to the initial raw mixture submitted to the MSR process, smaller ceramic grains were observed after sintering, which suggested that ceramic particle growth was hindered by the presence of Ta, Nb and/or Mo in the host titanium carbonitride structure. Nanoindentation measurements enabled the determination of the hardness of the ceramic and binder phases, and values in the range of 26–29 GPa and 14–16 GPa were found, respectively. The high hardness values of the binder were related to the formation of intermetallic phases.
May, 2016 · DOI: 10.1021/acsami.6b00232
Nanotecnología en Superficies y Plasma
Non-enzymatic Glucose electrochemical sensor made of porous NiO thin films prepared by reactive magnetron sputtering at oblique angles
Garcia-Garcia, FJ; Salazar, P; Yubero, F; Gonzalez-Elipe, ARElectrochimica Acta, 201 (2016) 38-44 DOI: 10.1016/j.electacta.2016.03.193

Abstract
Porous nanostructured NiO thin films have been prepared in one step by magnetron sputtering in an oblique angle configuration (MS-OAD) and used as electrodes for the non-enzymatic detection of glucose. The films have been thoroughly characterized by different complementary techniques and their performance for the analysis of glucose in basic solutions determined by electrochemical methods. These electrodes presented four times higher sensitivity that equivalent compact thin films prepared by MS in a normal configuration and were superior in terms of sensitivity than majority of nickel based electrodes prepared by other methods. Finally, a high sensitivity towards detection of glucose in blood, insensitivity to common interferences, a long term stability and high reproducibility confirmed the good performance and reliability of these electrodes for practical analytical purposes.
May, 2016 · DOI: 10.1016/j.electacta.2016.03.193
Materiales Ópticos Multifuncionales
A panchromatic modification of the light absorption spectra of metal-organic frameworks
Otal, E. H.; Kim, M. L.; Calvo, M. E.; Karvonen, L.; Fabregas, I. O.; Sierra, C. A.; Hinestroza, J. P.Chemical Communications, 52 (2016) 6665-6668 DOI: 10.1039/c6cc02319c

Abstract
The optical absorption of UiO-66–NH2 MOF was red-shifted using a diazo-coupling reaction. The modifications performed with naphthols and aniline yielded reddish samples, and the modifications with diphenylaniline yielded dark violet ones. The photocatalytic activity of these modified MOFs was assessed for methylene blue degradation, showing a good performance relative to traditional TiO2. The degradation performance was found to correlate with the red shift of the absorption edge. These findings suggest potential applications of these materials in photocatalysis and in dye sensitized solar cells.
May, 2016 · DOI: 10.1039/c6cc02319c
Reactividad de Sólidos
Electrical properties of reduced 3YTZP ceramics consolidated by spark plasma sintering
Poyato, R; Macias-Delgado, J; Garcia-Valenzuela, A; Gonzalez-Romero, RL; Munoz, A; Dominguez-Rodriguez, ACeramics International, 42 (2016) 6713-6719 DOI: 10.1016/j.ceramint.2016.01.040

Abstract
3 mol% Yttria doped zirconia ceramics were consolidated by spark plasma sintering (SPS) at two sintering temperatures with the aim of achieving two different reduction levels. Microstructural characterization of the ceramics was performed by scanning electron microscopy (SEM). Electrical properties were investigated by means of impedance spectroscopy from room temperature up to 500 degrees C. The two ceramics presented a remarkably different electrical behavior. The effect of the extra electrons introduced by reduction during SPS on both the bulk and the grain boundary conductivity was analyzed and discussed.
May, 2016 · DOI: 10.1016/j.ceramint.2016.01.040
Reactividad de Sólidos
Obtention of Li3xLa2/3−xTiO3 ceramics from amorphous nanopowders by spark plasma sintering
Leyet, Y.; Guerrero, F.; Anglada-Rivera, J.; Martinez, I.; Amorin, H.; Romaguera-Barcelay, Y.; Poyato, R.; Gallardo-Lopez, A.Ferroelectrics, 498 (2016) 62-66 DOI: 10.1080/00150193.2016.1167538
Abstract
In this work, Li3xLa2/3-xTiO3 powder with nominal lithium content (x = 0.08) was synthesized by mechano synthesis method. Spark plasma sintering (SPS) was employed to prepare lithium lanthanum titanium oxide solid-state ceramic. The techniques of X-ray diffraction, high resolution scanning electron microscopy, and Raman spectroscopy were used to characterize the composition and microstructure of samples. The results showed that fine-grained ceramics with relative density of 95.5% were obtained by sintering the oxide powders at 1100 degrees C for only 5min.
May, 2016 · DOI: 10.1080/00150193.2016.1167538
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Cascade charge separation mechanism by ternary heterostructured BiPO4/TiO2/g-C3N4 photocatalyst
Obregon, S; Zhang, YF; Colon, GApplied Catalysis B: Enviromental, 184 (2016) 96-103 DOI: 10.1016/j.apcatb.2015.11.027

Abstract
A complex ternary BiPO4/TiO2/gC(3)N(4) heterostructure has been obtained from a simple impregnation method having good photoactivities for the degradation of phenol under solar-like irradiation. From the wide structural, surface and electronic characterization, we have stated that the formation of the ternary heterojunction notably affect photoactivity of pristine TiO2. Thus, the best result for the binary system was obtained for 70 wt%TiO2-30 wt% BiPO4 system. The incorporation of gC(3)N(4) leads to a further improvement on the photocatalytic activity when it is specifically done over TiO2. By means of photoluminescence spectroscopy and reactive oxygen species formation test, we propose that the effective charge carrier separation is taking place through a cascade-driven electronic mechanism. Therefore, by choosing the adequate band-engineering tailoring an important improved photoactivity can be achieved.
May, 2016 · DOI: 10.1016/j.apcatb.2015.11.027
Reactividad de Sólidos
Effect of dolomite decomposition under CO2 on its multicycle CO2 capture behaviour under calcium looping conditions
Martos, AD; Valverde, JM; Sanchez-Jimenez, PE; Perejon, A; Garcia-Garrido, C; Perez-Maqueda, LAPhysical Chemistry Chemical Physics, 18 (2016) 16325-16336 DOI: 10.1039/c6cp01149g

Abstract
One of the major drawbacks that hinder the industrial competitiveness of the calcium looping (CaL) process for CO2 capture is the high temperature (∼930–950 °C) needed in practice to attain full calcination of limestone in a high CO2 partial pressure environment for short residence times as required. In this work, the multicycle CO2 capture performance of dolomite and limestone is analysed under realistic CaL conditions and using a reduced calcination temperature of 900 °C, which would serve to mitigate the energy penalty caused by integration of the CaL process into fossil fuel fired power plants. The results show that the fundamental mechanism of dolomite decomposition under CO2 has a major influence on its superior performance compared to limestone. The inert MgO grains resulting from dolomite decomposition help preserve a nanocrystalline CaO structure wherein carbonation in the solid-state diffusion controlled phase is promoted. The major role played by the dolomite decomposition mechanism under CO2 is clearly demonstrated by the multicycle CaO conversion behaviour observed for samples decomposed at different preheating rates. Limestone decomposition at slow heating rates yields a highly crystalline and poorly reactive CaCO3 structure that requires long periods to fully decarbonate and shows a severely reduced capture capacity in subsequent cycles. On the other hand, the nascent CaCO3 produced after dolomite half-decomposition consists of nanosized crystals with a fast decarbonation kinetics regardless of the preheating rate, thus fully decomposing from the very first cycle at a reduced calcination temperature into a CaO skeleton with enhanced reactivity as compared to limestone derived CaO.
May, 2016 · DOI: 10.1039/c6cp01149g
Química de Superficies y Catálisis
O-2-assisted Water Gas Shift reaction over structured Au and Pt catalysts
Gonzalez-Castano, M; Reina, TR; Ivanova, S; Tejada, LMM; Centeno, MA; Odriozola, JAApplied Catalysis B: Enviromental, 185 (2016) 337-343 DOI: 10.1016/j.apcatb.2015.12.032

Abstract
Platinum and gold structured catalysts were compared as active phases in classical and O2-assisted Water Gas Shift (WGS) reaction. Both metals were supported on iron-doped ceria mixed oxide and then, structured on metallic micromonolithic devices. As expected the WGS activity of both micromonoliths is conditioned by the nature of the noble metals being Pt the most active metal in traditional conditions. However, the addition of oxygen to the classical water gas feed turns the balance in favor of the gold based catalysts, being the presence of gold responsible for an excessive improvement of the catalytic activity.
May, 2016 · DOI: 10.1016/j.apcatb.2015.12.032
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Towards the hydrogen production by photocatalysis
Colon, GApplied Catalysis A-General, 518 (2016) 48-59 DOI: 10.1016/j.apcata.2015.11.042

Abstract
Nowadays, problems derived from climate change urgently demand us to focus our attention on new alternatives to fossil fuels. Within this framework, the photocatalytic production of hydrogen as a clean fuel from oxygenates arises as a necessary option that must be considered. Thus, the development of highly efficient photocatalyst is crucial in order to achieve a viable technology under the industrial point of view. For this sake, it is necessary to understand the principles of photoreforming reaction. In this brief review we will revisit the different photocatalytic materials proposed in the literature highlighting on the role of different co-catalysts.
May, 2016 · DOI: 10.1016/j.apcata.2015.11.042
Materiales Ópticos Multifuncionales
Solution processed high refractive index contrast distributed Bragg reflectors
Anaya, M; Rubino, A; Calvo, ME; Miguez, HJournal of Materials Chemistry C, 4 (2016) 4532-4537 DOI: 10.1039/C6TC00663A

Abstract
We have developed a method to alternate porous and dense dielectric films in order to build high refractive index contrast distributed Bragg reflectors (DBRs) capable of reflecting very efficiently in a targeted spectral range employing a small number of layers in the stack. Porous layers made of SiO2 nanoparticles and compact sol–gel processed TiO2 layers are sequentially deposited. The key to the preservation of porosity of every other layer during the deposition process is the use of a sacrificial layer of polystyrene that prevents the infiltration of the interstitial voids between nanoparticles with the homogeneous solution of TiO2 precursors. Our approach allows preparing a series of DBRs operating along the whole visible spectral range. Reflectance values as high as 90% are achieved from only seven layers. The particular distribution of porosity along one direction gives rise to an interesting interplay between the optical properties of the system and the vapor pressure in the surrounding atmosphere, which we foresee could be put into practice in gas sensing devices.
May, 2016 · DOI: 10.1039/C6TC00663A
Materiales de Diseño para la Energía y Medioambiente
Biological strategy for the fabrication of highly ordered aragonite helices: the microstructure of the cavolinioidean gastropods
Checa, AG; Macias-Sanchez, E; Ramirez-Rico, JScientific Reports, 6 (2016) article number 25989 DOI: 10.1038/srep25989

Abstract
The Cavolinioidea are planktonic gastropods which construct their shells with the so-called aragonitic helical fibrous microstructure, consisting of a highly ordered arrangement of helically coiled interlocking continuous crystalline aragonite fibres. Our study reveals that, despite the high and continuous degree of interlocking between fibres, every fibre has a differentiated organic-rich thin external band, which is never invaded by neighbouring fibres. In this way, fibres avoid extinction. These intra-fibre organic-rich bands appear on the growth surface of the shell as minuscule elevations, which have to be secreted differentially by the outer mantle cells. We propose that, as the shell thickens during mineralization, fibre secretion proceeds by a mechanism of contact recognition and displacement of the tips along circular trajectories by the cells of the outer mantle surface. Given the sizes of the tips, this mechanism has to operate at the subcellular level. Accordingly, the fabrication of the helical microstructure is under strict biological control. This mechanism of fibre-by-fibre fabrication by the mantle cells is unlike that any other shell microstructure.
May, 2016 · DOI: 10.1038/srep25989
Nanotecnología en Superficies y Plasma
The interaction between hybrid organic-inorganic halide perovskite and selective contacts in perovskite solar cells: an infrared spectroscopy study
Idigoras, J; Todinova, A; Sanchez-Valencia, JR; Barranco, A; Borras, A; Anta, JAPhysical Chemistry Chemical Physics, 18 (2016) 13583-13590 DOI: 10.1039/c6cp01265e

Abstract
The interaction of hybrid organic-inorganic halide perovskite and selective contacts is crucial to get efficient, stable and hysteresis-free perovskite-based solar cells. In this report, we analyze the vibrational properties of methylammonium lead halide perovskites deposited on different substrates by infrared absorption (IR) measurements (4000-500 cm(-1)). The materials employed as substrates are not only characterized by different chemical natures (TiO2, ZnO and Al2O3), but also by different morphologies. For all of them, we have investigated the influence of these substrate properties on perovskite formation and its degradation by humidity. The effect of selective-hole contact (Spiro-OmeTad and P3HT) layers on the degradation rate by moisture has also been studied. Our IR results reveal the existence of a strong interaction between perovskite and all ZnO materials considered, evidenced by a shift of the peaks related to the N-H vibrational modes. The interaction even induces a morphological change in ZnO nanoparticles after perovskite deposition, pointing to an acid-base reaction that takes place through the NH3+ groups of the methylammonium cation. Our IR and X-ray diffraction results also indicate that this specific interaction favors perovskite decomposition and PbI2 formation for ZnO/perovskite films subjected to humid conditions. Although no interaction is observed for TiO2, Al2O3, and the hole selective contact, the morphology and chemical nature of both contacts appear to play an important role in the rate of degradation upon exposure to moisture.
May, 2016 · DOI: 10.1039/c6cp01265e
Nanotecnología en Superficies y Plasma
Light management: porous 1-dimensional nanocolumnar structures as effective photonic crystals for perovskite solar cells
Ramos, FJ; Oliva-Ramirez, M; Nazeeruddin, MK; Graetzel, M; Gonzalez-Elipe, AR; Ahmad, SJournal of Materials Chemistry A, 4 (2016) 4962-4970 DOI: 10.1039/c5ta08743k

Abstract
Hybrid organic-inorganic perovskite solar cells are a topic of increasing interest, as in a short time span they are able to lead in the third generation photovoltaics. Organohalide perovskites possess exceptional optoelectronic and physical properties, thus making their implementation possible in many diverse configurations of photovoltaic devices. In this work, we present three different configurations of porous 1-dimensional photonic crystals (1-DPCs) based on alternated nanocolumnar layers of oxides with different refractive indices (n) that were deposited by Physical Vapor Deposition at Oblique Angle Deposition (PVD-OAD). They are then implemented as the photoanode in CH3NH3PbI3 solar cells to improve the management of light into the device. These configurations improved the performance of the photovoltaic system by designing a light interference structure capable of enhancing the absorption capability of the perovskite. A device fabricated using these photonic crystal structures presented an efficiency >12% in contrast with only 10.22% for a reference device based on non-photonic crystal TiO2 layers deposited under analogous conditions.
April, 2016 · DOI: 10.1039/c5ta08743k
Materiales Avanzados
Effect of lime on stabilization of phyllite clays
Garzon, E; Cano, M; O'Kelly, BC; Sanchez-Soto, PJApplied Clay Science, 123 (2016) 329-334 DOI: 10.1016/j.clay.2016.01.042

Abstract
This paper represents a new advance in the study of engineering properties and material applications of phyllite clays. Considering their potential use as construction materials for structures subjected to low stress levels, this laboratory research investigated the stabilization and improvement in engineering properties of a Spanish phyllite clay achieved by the addition of 3, 5 and 7 wt.% lime. Geotechnical properties investigated include the consistency limits, compaction, California Bearing Ratio, swelling potential and water-permeability. The phyllite clay–lime mixtures had good compaction properties and very to extremely low permeability-coefficient values, with a semi-logarithmic correlation between increasing permeability and increasing proportion of lime additive. The addition of 3 wt.% lime was sufficient to reach the index of capacity amble specified in the Sheet of Technical General Prescriptions for Works of Roads and Bridges PG–3 (Spanish Highways Agency, 2008), significantly reducing the plasticity index value, with the compacted mixture undergoing no swelling under soakage. The required pavement thicknesses for the raw phyllite–clay material and the phyllite clay–lime mixtures are compared and discussed. Potential applications for phyllite clay–lime mixtures include for pavements/road subgrade, earth construction, building materials and for impermeabilization purposes.
April, 2016 · DOI: 10.1016/j.clay.2016.01.042
Nanotecnología en Superficies y Plasma
Nickel-copper bilayer nanoporous electrode prepared by physical vapor deposition at oblique angles for the non-enzymatic determination of glucose
Salazar, P; Rico, V; Gonzalez-Elipe, ARSensors and Actuators B: Chemical, 226 (2016) 436-443 DOI: 10.1016/j.snb.2015.12.003

Abstract
This work presents a novel bilayer Ni/Cu porous nanostructured film electrode prepared by physical vapor deposition (PVD) in an oblique angle configuration. Scanning electron microscopy (SEM) data revealed that the film, with an approximate thickness of 200 nm, is formed by tilted nanocolumns of around 50 nm of diameter and an inclination of 30° with respect to the surface normal. X ray photoelectron spectroscopy (XPS) data confirmed a bilayer configuration with Cu and Ni located at the top and bottom parts of the film, respectively. A porosity of ca. 45–35% as determined by Rutherford back scattering (RBS) offered a large exposed area and excellent diffusion properties that, combined with a very good catalytic activity, rendered these films excellent electrodes for the quantitative determination of glucose. Under optimized working conditions of detection these electrodes presented a high sensitivity of 2.53 A M−1 cm−2 (R2: 0.999), a limit of detection of 0.23 μM and a time response of ca. 2 s. The sensors did not show any loss of response during a period of 4 months. The selectivity of the sensor was checked against various interferences, including physiological compounds, different sugars and ethanol, in all cases with excellent results. The feasibility of using of this sensor for practical applications was confirmed by successfully determining the glucose content in different commercial beverages.
April, 2016 · DOI: 10.1016/j.snb.2015.12.003
Materiales de Diseño para la Energía y Medioambiente
Strength and microplasticity of biocarbons prepared by carbonization in the presence of a catalyst
Shpeizman, VV; Orlova, TS; Smirnov, BI; Gutierrez-Pardo, A; Ramirez-Rico, JPhysics of the Solid State, 58 (2016) 703-710 DOI: 10.1134/S1063783416040223
Abstract
The microdeformation has been investigated under uniaxial compression of beech-derived biocarbons partially graphitized during carbonization in the presence of a Ni- or Fe-containing catalyst. The strength and ultimate fracture strain have been determined at different temperatures of carbonization of the samples in the absence or in the presence of a catalyst. It has been shown using high-precision interferometry that the deformation of biocarbon samples under uniaxial loading occurs through jumps (in magnitude and rate of deformation) with axial displacements in the nanometer and micrometer ranges. The use of a catalyst leads to a decrease in the size of nanometer-scale jumps and in the number of micrometer-scale jumps. The standard deviations of the strain rate on loading steps from the smooth average dependence of the strain rate on the displacement have been calculated for micrometer-scale jumps. A similar characteristic for nanometer- scale jumps has been determined from the distortion of the shape of beats in the primary interferogram. It has been shown that the variation in the standard deviation of the strain rate with a change in the carbonization temperature is similar to the corresponding dependence of the ultimate fracture strain.
April, 2016 · DOI: 10.1134/S1063783416040223
The Structure and Chemical Composition of Wall Paintings From Islamic and Christian Times in the Seville Alcazar
Robador, MD; De Viguerie, L; Perez-Rodriguez, JL; Rousseliere, H; Walter, P; Castaing, JArchaeometry, 58 (2016) 255-270 DOI: 10.1111/arcm.12218

Abstract
Wall paintings from the Islamic epoch (10th to 12th centuries) and the Christian monarchy (14th to 16th centuries) have been recovered in discarded materials and on walls after reconstruction works in the Seville Alcazar. These paintings have spent centuries underground or under a plaster coat. Portable X-ray fluorescence (XRF) and combined XRF/X-ray diffraction (XRD) were employed in situ, as well as scanning electron microscopy (SEM-EDX), grazing angle incidence XRD and micro-Raman spectroscopy, on cross-section samples to fully characterize the materials in the wall paintings. Using these methods, the fresco technique was demonstrated, and many kinds of pigments were identified in accordance with the various periods of the history of the Alcazar, thus assessing the authenticity of all the wall paintings studied here.
April, 2016 · DOI: 10.1111/arcm.12218
Materiales Coloidales
Transparent polycrystalline SrREGa3O7 melilite ceramics: potential phosphors for tuneable solid state lighting
Boyer, M; Carrion, AJF; Ory, S; Becerro, AI; Villette, S; Eliseeva, SV; Petoud, S; Aballea, P; Matzen, G; Allix, MJournal of Materials Chemistry C, 15 (2016) 3238-3247 DOI: 10.1039/C6TC00633G

Abstract
Full and congruent crystallization from glass is applied to the SrREGa3O7 melilite family (RE = Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y). This innovative process enables the synthesis of polycrystalline ceramics exhibiting high transparency both in the visible and near infrared regions, despite tetragonal crystal structures and micrometer scale grain sizes. Moreover, glass crystallization provides an original route to synthesize new crystalline phases which are not accessible via a classic solid state reaction, as demonstrated for SrYbGa3O7 and SrTmGa3O7. To illustrate the potential optical applications of such materials, SrGdGa3O7 transparent polycrystalline ceramics are doped with Dy3+ or Tb3+/Eu3+ in order to generate white light emission under UV excitation. It is foreseen that such transparent melilite ceramic phosphors, prepared via a cost-effective process, can be successfully used in solid state lighting devices of considerable technological interest.
April, 2016 · DOI: 10.1039/C6TC00633G
Tribología y Protección de Superficies
Structure, electrochemical properties and functionalization of amorphous CN films deposited by femtosecond pulsed laser ablation
Maddi, C; Bourquard, F; Tite, T; Loir, AS; Donnet, C; Garrelie, F; Barnier, V; Wolski, K; Fortgang, P; Zehani, N; Braiek, M; Lagarde, F; Chaix, C; Jaffrezic-Renault, N; Rojas, TC; Sanchez-Lopez, JCDiamond and Related Materials,65 (2016) 17-25 DOI: 10.1016/j.diamond.2016.01.001

Abstract
Amorphous carbon nitride (a-C:N) material has attracted much attention in research and development Recently, it has become a more promising electrode material than conventional carbon based electrodes in electrochemical and biosensor applications. Nitrogen containing amorphous carbon (a-C:N) thin films have been synthesized by femtosecond pulsed laser deposition (fs-PLD) coupled with plasma assistance through Direct Current (DC) bias power supply. During the deposition process, various nitrogen pressures (0 to 10 Pa) and DC bias (0 to -350 V) were used in order to explore a wide range of nitrogen content into the films. The structure and chemical composition of the films have been studied by using Raman spectroscopy, electron energy-loss spectroscopy (EELS) and high-resolution transmission electron microscopy (HRTEM). Increasing the nitrogen pressure or adding a DC bias induced an increase of the N content, up to 21 at%. Nitrogen content increase induces a higher sp(2) character of the film. However DC bias has been found to increase the film structural disorder, which was detrimental to the electrochemical properties. Indeed the electrochemical measurements, investigated by cyclic voltammetry (CV), demonstrated that a-C:N film with moderate nitrogen content (10 at.%) exhibited the best behavior, in terms of reversibility and electron transfer kinetics. Electrochemical grafting from diazonium salts was successfully achieved on this film, with a surface coverage of covalently bonded molecules close to the dense packed monolayer of ferrocene molecules. Such a film may be a promising electrode material in electrochemical detection of electroactive pollutants on bare film, and of biopathogen molecules after surface grafting of the specific affinity receptor.
April, 2016 · DOI: 10.1016/j.diamond.2016.01.001
Materiales Ópticos Multifuncionales
Effect of temperature variations on equilibrium distances in levitating parallel dielectric plates interacting through Casimir forces
Esteso, V; Carretero-Palacios, S; Miguez, HJournal of Applied Physics, 119 (2016) 144301 DOI: 10.1063/1.4945428
Abstract
We study at thermal equilibrium the effect of temperature deviations around room temperature on the equilibrium distance (d(eq)) at which thin films made of Teflon, silica, or polystyrene immersed in glycerol levitate over a silicon substrate due to the balance of Casimir, gravity, and buoyancy forces. We find that the equilibrium nature (stable or unstable) of d(eq) is preserved under temperature changes, and provide simple rules to predict whether the new equilibrium position will occur closer to or further from the substrate at the new temperature. These rules depend on the static permittivities of all materials comprised in the system (epsilon((m))(0)) and the equilibrium nature of d(eq). Our designed dielectric configuration is excellent for experimental observation of thermal effects on the Casimir force indirectly detected through the tunable equilibrium distances (with slab thickness and material properties) in levitation mode.
April, 2016 · DOI: 10.1063/1.4945428
Nanotecnología en Superficies y Plasma
Growth Assisted by Glancing Angle Deposition: A New Technique to Fabricate Highly Porous Anisotropic Thin Films
Sanchez-Valencia, JR; Longtin, R; Rossell, MD; Groning, PACS Applied Materials & Interfaces, 8 (2016) 8686-8693 DOI: 10.1021/acsami.6b00232

Abstract
We report a new methodology based on glancing angle deposition (GLAD) of an organic molecule in combination with perpendicular growth of a second inorganic material. The resulting thin films retain a very well-defined tilted columnar microstructure characteristic of GLAD with the inorganic material embedded inside the columns. We refer to this new methodology as growth assisted by glancing angle deposition or GAGLAD, since the material of interest (here, the inorganic) grows in the form of tilted columns, though it is deposited under a nonglancing configuration. As a “proof of concept”, we have used silver and zinc oxide as the perpendicularly deposited material since they usually form ill-defined columnar microstructures at room temperature by GLAD. By means of our GAGLAD methodology, the typical tilted columnar microstructure can be developed for materials that otherwise do not form ordered structures under conventional GLAD. This simple methodology broadens significantly the range of materials where control of the microstructure can be achieved by tuning the geometrical deposition parameters. The two examples presented here, Ag/Alq3 and ZnO/Alq3, have been deposited by physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD), respectively: two different vacuum techniques that illustrate the generality of the proposed technique. The two type of hybrid samples present very interesting properties that demonstrate the potentiality of GAGLAD. On one hand, the Ag/Alq3 samples present highly optical anisotropic properties when they are analyzed with linearly polarized light. To our knowledge, these Ag/Alq3 samples present the highest angular selectivity reported in the visible range. On the other hand, ZnO/Alq3 samples are used to develop highly porous ZnO thin films by using Alq3 as sacrificial material. In this way, antireflective ZnO samples with very low refractive index and extinction coefficient have been obtained.
April, 2016 · DOI: 10.1021/acsami.6b00232
Química de Superficies y Catálisis
Nanogold mesoporous iron promoted ceria catalysts for total and preferential CO oxidation reactions
Reina, TR; Ivanova, S; Idakiev, V; Tabakova, T; Centeno, MA; Deng, QF; Yuan, ZY; Odriozola, JAJournal of Molecular Catalysis A-Chemical, 414 (2016) 62-71 DOI: 10.1016/j.molcata.2016.01.003

Abstract
Herein, a series of highly efficient gold based catalysts supported on mesoporous CeO2-Fe2O3 mixed oxides for CO elimination reactions have been developed. The materials have been fully characterized by means of XRD, Raman and UV-vis spectroscopies among other techniques. We identify the Ce-Fe synergism as a fundamental factor controlling the catalytic performance. Our data clearly reveal that the CO oxidation activity is maximized when the electronic and structural properties of the support are carefully controlled. In this situation, fairly good catalysts for environmental applications as for example H-2 streams purification for fuel cell goals or CO abatement at room temperature can be designed.
April, 2016 · DOI: 10.1016/j.molcata.2016.01.003
Nanotecnología en Superficies y Plasma
Pre-prosthetic use of poly(lactic-co-glycolic acid) membranes treated with oxygen plasma and TiO2 nanocomposite particles for guided bone regeneration processes
Castillo-Dali, G; Castillo-Oyague, R; Terriza, A; Saffar, JL; Batista-Cruzado, A; Lynch, CD; Sloan, AJ; Gutierrez-Perez, JL; Torres-Lagares, DJournal of Dentistry, 47 (2016) 71-79 DOI: 10.1016/j.jdent.2016.01.015
Abstract
Objectives: Guided bone regeneration (GBR) processes are frequently necessary to achieve appropriate substrates before the restoration of edentulous areas. This study aimed to evaluate the bone regeneration reliability of a new poly-lactic-co-glycolic acid (PLGA) membrane after treatment with oxygen plasma (PO2) and titanium dioxide (TiO2) composite nanoparticles.
Methods: Circumferential bone defects (diameter: 10 mm; depth: 3 mm) were created on the parietal bones of eight experimentation rabbits and were randomly covered with control membranes (Group 1: PLGA) or experimental membranes (Group 2: PLGA/PO2/TiO2). The animals were euthanized two months afterwards, and a morphologic study was then performed under microscope using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone formed in the grown defects, concentration of osteoclasts, and intensity of osteosynthetic activity were assessed. Comparisons among the groups and with the original bone tissue were made using the Kruskal-Wallis test. The level of significance was set in advance at a = 0.05.
Results: The experimental group recorded higher values for new bone formation, mineralised bone length, and osteoclast concentration; this group also registered the highest osteosynthetic activity. Bone layers in advanced formation stages and low proportions of immature tissue were observed in the study group.
April, 2016 · DOI: 10.1016/j.jdent.2016.01.015
Materiales Avanzados
Ceramics from clays and by-product from biodiesel production: Processing, properties and microstructural characterization
Martinez-Martinez, S; Perez-Villarejo, L; Eliche-Quesada, D; Carrasco-Hurtado, B; Sanchez-Soto, PJ; Angelopoulos, GNApplied Clay Science, 121 (2016) 119-126 DOI: 10.1016/j.day.2015.12.003

Abstract
The production of biodiesel generates a by-product called glycerine which contains glycerol that cannot be reintegrated into the same manufacturing process. The ceramic bricks are an interesting option to set in their structure a wide range of by-products and residues materials and composites, sometimes serving only as a reservoir for the inert residue, and other, having a positive effect on the ceramic material or process. In the present work, the incorporation of this waste in raw clays has been studied. The raw materials: clay and glycerine was characterized by XRD, XRF, CNHS analysis, higher heating value and thermal analysis and after, using conventional moulding and sintering processing methods to prepare clay-glycerine composites, the influence of the amount of waste added to clay has been evaluated. To do this, percentages of glycerine were added to the clay from 5% to 20% and evaluated by a series of technological properties such as compressive strength, absorption and suction of water, bulk density, the study of porosity generated by adsorption-desorption isotherms of N-2, thermal conductivity and finally by the compressive strength after freezing-thaw, it was considered as the maximum permissible rate of addition of glycerol 10-15% in weight, because higher additions have a strong effect on the properties of the obtained materials such as compression strength and bulk density which descending dramatically due to the large amount of porosity generated as reflected by high values of absorption and suction experiments. It was concluded that adding 5% glycerol to the ceramic paste generated plasticity in clay to achieve be moulded, with values of compressive strength of 84 MPa while gets to reduce the density apparent by almost.
March, 2016 · DOI: 10.1016/j.day.2015.12.003
Materiales de Diseño para la Energía y Medioambiente
Active metal brazing of silicon nitride ceramics using a Cu-based alloy and refractory metal interlayers
Fernandez, JM; Asthana, R; Singh, M; Valera, FMCeramics International, 42 (2016) 5447-5454 DOI: 10.1016/j.ceramint.2015.12.087

Abstract
Silicon nitride/silicon nitride joints with refractory metal (W and Mo) interlayers were vacuum brazed using an active braze, Cu-ABA (Cu-3Si-2Al-2.25Ti, wt%), and two interlayer arrangements in a double-lap offset configuration: Si3N4/Cu-ABA/W/Cu-ABA/Mo/Cu-ABA/Si3N4 and Si3N4/Cu-ABA /Si3N4. Titanium segregated at the Si3N4/Cu-ABA and Mo/Cu-ABA interfaces, but not at the W/Cu-ABA interface. The room-temperature compression-shear strength values of Si3N4/Cu-ABA/Si3N4 and Si3N4/Cu-ABA/W/Cu-ABA/Mo/Cu-ABA/Si3N4 joints were 118 +/- 24 MPa and 22 +/- 5 MPa, respectively. Elevated-temperature compression tests showed that Si3N4/Cu-ABA/Si3N4 joints had strength of 31 +/- 6 MPa at 1023 K and 17 +/- 3 MPa at 1073 K. Likewise, Si3N4/Cu-ABA/W/Cu-ABA/Mo/Cu-ABA/Si3N4 joints had strength of 19 +/- 4 MPa at 1023 K and 13 +/- 3 MPa at 1073 K. Knoop microhardness profiles revealed hardness gradients across the joints. The effect of joint microstructure and test configuration on the mechanical behavior is discussed.
March, 2016 · DOI: 10.1016/j.ceramint.2015.12.087
Química de Superficies y Catálisis - Reactividad de Sólidos
Intensification of hydrogen production by methanol steam reforming
Sanz, O; Velasco, I; Perez-Miqueo, I; Poyato, R; Odriozola, JA; Montes, MInternational Journal Hydrogen Energy, 41 (2016) 5250-5259 DOI: 10.1016/j.ijhydene.2016.01.084

Abstract
This paper studies the methanol steam reforming intensification to enhance the hydrogen production in a multi-channel block type micro-reformer. The effects of operating parameters such as reforming temperature, space velocity and catalyst layer thickness on reforming performance are investigated. For optimized design and operating conditions, the 8 cm(3) reformer unit produced 170 LH2/h containing on dry basis 75.0% H-2, 23.5% CO2, 0.06% CH3OH and 1.44% CO at 648 K allowing the production of 218-255 Win a commercial PEMFC with 80% hydrogen utilization. This study shows that high methanol conversion can be achieved with high Pd/ZnO catalyst loading at 648 K with very low CO content (<1.5%) in the outlet stream.
March, 2016 · DOI: 10.1016/j.ijhydene.2016.01.084
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
TiO2-clay based nanoarchitectures for enhanced photocatalytic hydrogen production
Perez-Carvajal, J; Aranda, P; Obregon, S; Colon, G; Ruiz-Hitzky, EMicroporous and Mesoporous Materials, 222 (2016) 120-127 DOI: 10.1016/j.micromeso.2015.10.007

Abstract
New functional TiO2-clay nanoarchitectures based on layered and fibrous silicates and incorporating Pd and Pt noble metal nanoparticles (NPs) have been synthesized by applying a sol–gel methodology that involves the use of commercial organoclays. The incorporation of the noble metal NPs can be done using two different approaches: i) direct addition to the synthesis medium of a noble metal precursor (typically acetylacetonate) during the generation of the nanoarchitecture, and ii) selective photodeposition of the noble metal NPs in a post-treatment of the TiO2-clay nanoarchitecture. The resulting materials have been characterized by means of XRD, FTIR, Raman, 29Si-NMR, FE-SEM, TEM and N2 adsorption–desorption isotherms. The efficiency of these nanoarchitectures in the photocatalytic hydrogen production has been tested in the photoreforming of methanol. The higher rate in the hydrogen production corresponds to the nanoarchitectures containing Pt and TiO2 NPs derived from sepiolite.
March, 2016 · DOI: 10.1016/j.micromeso.2015.10.007
Nanotecnología en Superficies y Plasma
Characterization and application of a new pH sensor based on magnetron sputtered porous WO3 thin films deposited at oblique angles
Salazar, P; Garcia-Garcia, FJ; Yubero, F; Gil-Rostra, J; Gonzalez-Elipe, ARElectrochimica Acta, 193 (2016) 24-31 DOI: 10.1016/j.electacta.2016.02.040

Abstract
In this communication we report about an outstanding solid-state pH sensor based on amorphous nanocolumnar porous thin film electrodes. Transparent WO3 thin films were deposited by reactive magnetron sputtering in an oblique angle configuration to enhance their porosity onto indium tin oxide (ITO) and screen printed electrodes (SPE). The potentiometric pH response of the nanoporous WO3-modified ITO electrode revealed a quasi-Nernstian behaviour, i.e. a linear working range from pH 1 to 12 with a slope of about -57.7 mV/pH. pH detection with this electrode was quite reproducible, displayed excellent anti-interference properties and a high stable response that remained unaltered over at least 3 months. Finally, a pH sensor was developed using nanoporous WO3-modified screen printed electrode (SPE) using a polypyrrole-modified Ag/AgCl electrode as internal reference electrode. This full solid state pH sensor presented a Nernstian behaviour with a slope of about -59 mV/pH and offered important analytical and operation advantages for decentralized pH measurements in different applications.
March, 2016 · DOI: 10.1016/j.electacta.2016.02.040
Materiales Ópticos Multifuncionales
High-Throughput Fabrication of Resonant Metamaterials with Ultrasmall Coaxial Apertures via Atomic Layer Lithography
Yoo, D; Nguyen, NC; Martin-Moreno, L; Mohr, DA; Carretero-Palacios, S; Shaver, J; Peraire, J; Ebbesen, TW; Oh, SHNano Letters, 16 (2016) 2040-2046 DOI: 10.1021/acs.nanolett.6b00024

Abstract
We combine atomic layer lithography and glancing angle ion polishing to create wafer-scale metamaterials composed of dense arrays of ultrasmall coaxial nanocavities in gold films. This new fabrication scheme makes it possible to shrink the diameter and increase the packing density of 2 nm-gap coaxial resonators, an extreme subwavelength structure first manufactured via atomic layer lithography, both by a factor of 100 with respect to previous studies. We demonstrate that the nonpropagating zeroth-order Fabry-Perot mode, which possesses slow light-like properties at the cutoff resonance, traps infrared light inside 2 nm gaps (gap volume similar to lambda(3)/10(6)). Notably, the annular gaps cover only 3% or less of the metal surface, while open-area normalized transmission is as high as 1700% at the epsilon-near-zero (ENZ) condition. The resulting energy accumulation alongside extraordinary optical transmission can benefit applications in nonlinear optics, optical trapping, and surface-enhanced spectroscopies. Furthermore, because the resonance wavelength is independent of the cavity length and dramatically red shifts as the gap size is reduced, large-area arrays can be constructed with lambda(resonance) >> period, making this fabrication method ideal for manufacturing resonant metamaterials.
March, 2016 · DOI: 10.1021/acs.nanolett.6b00024
Materiales Ópticos Multifuncionales
Integration of Photonic Crystals into Flexible Dye Solar Cells: A Route toward Bendable and Adaptable Optoelectronic Devices Displaying Structural Color and Enhanced Efficiency
Li, YL; Calvo, ME; Miguez, HAdvanced Optical Materials, 4 (2016) 464-471 DOI: 10.1002/adom.201500547

Abstract
Herein is presented what is believed to be the first example of integration of photonic structures in a flexible optoelectronic device. The resulting devices may be designed to display any color in the visible range and, simultaneously, present enhanced power conversion efficiency as a consequence of the increased light harvesting caused by the colored back reflection. The achievement results from the incorporation of nanoparticle-based multilayers with photonic crystal properties that are modified to be compatible with the chemical and physical processing of flexible nanocrystalline titania electrodes of dye solar cells. The photovoltaic performance of these colored flexible cells remains unaltered after one hundred bending cycles, thus showing the high-mechanical stability of the ensemble. These devices reunite most characteristics required for building integration or for the construction of solar window panes, such as light weight, stability upon bending, adaptability, and color. This work may trigger promising applications of these highly adaptable and versatile photonic crystals in other flexible devices.
March, 2016 · DOI: 10.1002/adom.201500547
Materiales Nanoestructurados y Microestructura
Nitrogen Nanobubbles in a-SiOxNy Coatings: Evaluation of Its Physical Properties and Chemical Bonding State by Spatially Resolved Electron Energy-Loss Spectroscopy
Lacroix, B.; Godinho, V.; Fernández, A.Journal of Physical Chemistry C, 120 (2016) 5651-5658 DOI: 10.1021/acs.jpcc.5b09036

Abstract
Nanoporous silicon-based materials with closed porosity filled with the sputtering gas have been recently developed by magnetron sputtering. In this work the physical properties (density and pressure) of molecular nitrogen inside closed pores in a SiOxNy coating are investigated for the first time using spatially resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope. The paper offers a detailed methodology to record and process multiple EELS spectrum images (SIs) acquired at different energy ranges and with different dwell times. An adequate extraction and quantification of the N–K edge contribution due to the molecular nitrogen inside nanopores is demonstrated. Core-loss intensity and N chemical bond state were evaluated to retrieve 2D maps revealing the stable high density of molecular nitrogen (from 40 to 70 at./nm3) in nanopores of different size (20–11 nm). This work provides new insights into the quantification of molecular N2 trapped in porous nitride matrices that could also be applied to other systems.
March, 2016 · DOI: 10.1021/acs.jpcc.5b09036
Reactividad de Sólidos
Fabrication and characterization of CeO2 pellets for simulation of nuclear fuel
Garcia-Ostos, C; Rodriguez-Ortiz, JA; Arevalo, C; Cobos, J; Gotor, FJ; Torres, YNuclear Engineering and Design, 298 (2016) 160-167 DOI: 10.1016/j.nucengdes.2015.12.026

Abstract
Cerium Oxide, CeO2, has been shown as a surrogate material to understand irradiated Mixed Oxide (MOX) based matrix fuel for nuclear power plants due to its similar structure, chemical and mechanical properties. In this work, CeO2 pellets with controlled porosity have been developed through conventional powder-metallurgy process. Influence of the main processing parameters (binder content, compaction pressure, sintering temperature and sintering time) on porosity and volumetric contraction values has been studied. Microstructure and physical properties of sintered compacts have also been characterized through several techniques. Mechanical properties such as dynamic Young's modulus, hardness and fracture toughness have been determined and connected to powder-metallurgy parameters. Simulation of nuclear fuel after reactor utilization with radial gradient porosity is proposed.
March, 2016 · DOI: 10.1016/j.nucengdes.2015.12.026
Nanotecnología en Superficies y Plasma
Perspectives on oblique angle deposition of thin films: From fundamentals to devices
Barranco, A; Borras, A; Gonzalez-Elipe, AR; Palmero, AProgress in Materials Science, 78 (2016) 59-153 DOI: 10.1016/j.pmatsci.2015.06.003

Abstract
The oblique angle configuration has emerged as an invaluable tool for the deposition of nanostructured thin films. This review develops an up to date description of its principles, including the atomistic mechanisms governing film growth and nanostructuration possibilities, as well as a comprehensive description of the applications benefiting from its incorporation in actual devices. In contrast with other reviews on the subject, the electron beam assisted evaporation technique is analyzed along with other methods operating at oblique angles, including, among others, magnetron sputtering and pulsed laser or ion beam-assisted deposition techniques. To account for the existing differences between deposition in vacuum or in the presence of a plasma, mechanistic simulations are critically revised, discussing well-established paradigms such as the tangent or cosine rules, and proposing new models that explain the growth of tilted porous nanostructures. In the second part, we present an extensive description of applications wherein oblique-angle-deposited thin films are of relevance. From there, we proceed by considering the requirements of a large number of functional devices in which these films are currently being utilized (e.g., solar cells, Li batteries, electrochromic glasses, biomaterials, sensors, etc.), and subsequently describe how and why these nanostructured materials meet with these needs.
March, 2016 · DOI: 10.1016/j.pmatsci.2015.06.003
Fotocatálisis Heterogénea: Aplicaciones
Comparison of supported TiO2 catalysts in the photocatalytic degradation of NOx
Rodriguez, MJH; Melian, EP; Diaz, OG; Arana, J; Macias, M; Orive, AG; Rodriguez, JMDJournal of Molecular Catalysis A-Chemical, 413 (2016) 56-66 DOI: 10.1016/j.molcata.2015.12.007

Abstract
A comparison is made in this study of the effectiveness of various commercial catalysts in the oxidation of NOx by heterogeneous photocatalysis. The following catalysts were considered: Aeroxide TiO2 P25, Aeroxide TiO2 P90, Hombikat UV-100, Kronos vlp7000, CristalACTIV PC105, CristalACTIV PC500, Kemira 650 and Anatasa Aldrich. All catalysts were deposited by a dip -coating technique onto borosilicate 3.3 glass plates. Optimization of catalyst load showed no significant enhancement of photoactivity, in general, above a deposited mass of 1.16 mg cm(-2). Differences between photocatalyst activity were more apparent at longer illumination times. Photoactivity decreased in the presence of humidity and differences in the adsorbed products were detected. Photocatalyst activity was strongly influenced by specific surface area, with the best results obtained by the catalysts with the largest surface area, namely the PC500, Hombikat and Kronos. Photocatalyst stability was demonstrated in successive reuse cycles.
March, 2016 · DOI: 10.1016/j.molcata.2015.12.007
Nanotecnología en Superficies y Plasma
Electrocatalytic System for the Simultaneous Hydrogen Production and Storage from Methanol
Gonzalez-Cobos, J; Rico, VJ; Gonzalez-Elipe, AR; Valverde, JL; de Lucas-Consuegra, AACS Catalysis, 6 (2016) 1942-1951 DOI: 10.1021/acscatal.5b02844

Abstract
This paper reports a groundbreaking approach for simultaneous hydrogen production and storage that entails catalysis, electrochemistry, surface science, and materials synthesis. A novel electrocatalytic system is developed based on nickel nanocolumnar films of controlled microstructure prepared on K-βAl2O3 solid electrolyte supports by oblique angle physical vapor deposition. The outstanding characteristics of this system are a hydrogen storage capacity of up to 19 g of H2 (100 g of Ni)−1, which is unparalleled in the literature and the possibility of controlling its release electrochemically, under fixed mild conditions (280 °C and normal pressure). H2 is produced in situ by methanol steam re-forming on the Ni catalyst, and it spills over onto graphene oxide aggregates formed during the catalytic process, as confirmed by SEM, FTIR, and Raman spectroscopy. The proposed storage mechanism considers a synergetic contribution of both Ni and graphene oxide, promoted by K+ ions, in enhancing the hydrogen storage capacity of the system.
March, 2016 · DOI: 10.1021/acscatal.5b02844
Nanotecnología en Superficies y Plasma
Nanoindentation and scratch resistance of multilayered TiO2-SiO2 coatings with different nanocolumnar structures deposited by PV-OAD
Roa, JJ; Rico, V; Oliva-Ramirez, M; Gonzalez-Elipe, AR; Jimenez-Pique, EJournal of Physics D-Applied Physics, 49 (2016) 13 DOI: 10.1088/0022-3727/49/13/135104
Abstract
This paper presents a study of the mechanical properties and an evaluation of damage mechanisms of nanocolumnar TiO2-SiO2 multilayer coatings prepared by physical vapour oblique angle deposition at different configurations (slanted, zigzag or chiral) and two zenithal evaporation angles (70 degrees or 85 degrees). The characterization at micro-and nanometric length scales of the mechanical properties of the multilayers has been carried out by nanoindentation and nanoscratch tests, while the morphological evaluation of the surface and sub-surface damages produced with a sharp indenter and the adhesive and/or cohesive failures between coating and substrate have been investigated by field emission scanning electron microscopy and focused ion beam, respectively. The obtained results have shown that the main processing parameters controlling the mechanical response of the different multilayers is the zenithal angle of deposition and the number of layers in the multilayer stack, while the coating architecture had only a minor effect on the mechanical response. This analysis also revealed a higher resistance to scratch testing and a brittle failure behaviour for the low zenithal angle coatings as compared with the high angle ones.
February, 2016 · DOI: 10.1088/0022-3727/49/13/135104
Materiales Ópticos Multifuncionales
Maximized performance of dye solar cells on plastic: a combined theoretical and experimental optimization approach
Li, Yuelong; Carretero-Palacios, Sol; Yoo, Kicheon; Kim, Jong Hak; Jimenez-Solano, Alberto; Lee, Chul-Ho; Miguez, Hernan; Ko, Min JaeEnergy & Environmental Science, 9 (2016) 2061-2071 DOI: 10.1039/C6EE00424E

Abstract
We demonstrate that a combined optimization approach based on the sequential alternation of theoretical analysis and experimental realization gives rise to plastic supported dye solar cells for which both light harvesting efficiency and electron collection are maximized. Rationalized configurations with optimized light trapping and charge extraction are realized to achieve photoanodes on plastic prepared at low temperature, showing a power conversion efficiency of 8.55% and a short circuit photocurrent of 16.11 mA cm−2, unprecedented for plastic based dye solar cell devices. Furthermore, the corresponding fully flexible designs present stable mechanical properties after several bending cycles, displaying 7.79% power conversion efficiency, an average broadband internal quantum efficiency above 90%, and a short circuit photocurrent of 15.94 mA cm−2, which is the largest reported value for bendable cells of this sort to date.
February, 2016 · DOI: 10.1039/C6EE00424E
Química de Superficies y Catálisis
In-situ Raman spectroscopy study of Ru/TiO2 catalyst in the selective methanation of CO
Martinez Tejada, LM; Munoz, A; Centeno, MA; Odriozola, JAJournal of Raman Spectroscopy, 47 (2016) 189-197 DOI: 10.1002/jrs.4774

Abstract
Raman spectroscopic technique has been used to characterize a Ru/TiO2 catalyst and to follow in situ their structural changes during the CO selective methanation reaction (S-MET). For a better comprehension of the catalytic mechanism, the in-situ Raman study of the catalysts activation (reduction) process, the isolated CO and CO2 methanation reactions and the effect of the composition of the reactive stream (H2O and CO2 presence) have been carried out. Raman spectroscopy evidences that the catalyst is composed by islands of TiO2-RuO2 solid solutions, constituting Ru-TiO2 interphases in the form of RuxTi1-xO2 rutile type solid solutions. The activation procedure with H-2 at 300 degrees C promotes the reduction of the RuO2-TiO2 islands generating Ru-o-Ti3+ centers. The spectroscopic changes are in agreement with the strong increase in chemical reactivity as increasing the carbonaceous intermediates observed. The selective methanation of CO proceeds after their adsorption on these Ru-o-Ti3+ active centers and subsequent C?O dissociation throughout the formation of CHx/CnHx/CnHxO/CHx?CO species. These intermediates are transformed into CH4 by a combination of hydrogenation reactions. The formation of carbonaceous species during the methanation of CO and CO2 suggests that the CO presence is required to promote the CO2 methanation. Similar carbonaceous species are detected when the selective CO methanation is carried out with water in the stream. However, the activation of the catalysts occurs at much lower temperatures, and the carbon oxidation is favored by the oxidative effect of water.
February, 2016 · DOI: 10.1002/jrs.4774
Materiales Ópticos Multifuncionales
Photophysical Analysis of the Formation of Organic–Inorganic Trihalide Perovskite Films: Identification and Characterization of Crystal Nucleation and Growth
Anaya, M; Galisteo-Lopez, JF; Calvo, ME; Lopez, C; Miguez, HJournal of Physical Chemistry C, 120 (2016) 3071-3076 DOI: 10.1021/acs.jpcc.6b00398

Abstract
In this work we demonstrate that the different processes occurring during hybrid organic–inorganic lead iodide perovskite film formation can be identified and analyzed by a combined in situ analysis of their photophysical and structural properties. Our observations indicate that this approach permits unambiguously identifying the crystal nucleation and growth regimes that lead to the final material having a cubic crystallographic phase, which stabilizes to the well-known tetragonal phase upon cooling to room temperature. Strong correlation between the dynamic and static photoemission results and the temperature-dependent X-ray diffraction data allows us to provide a description and to establish an approximate time scale for each one of the stages and their evolution. The combined characterization approach herein explored yields key information about the kinetics of the process, such as the link between the evolution of the defect density during film formation, revealed by a fluctuating photoluminescence quantum yield, and the gradual changes observed in the PbI2-related precursor structure.
February, 2016 · DOI: 10.1021/acs.jpcc.6b00398
Reactividad de Sólidos
Synthesis and characterization of CuInS2 nanocrystalline semiconductor prepared by high-energy milling
Dutkova, E; Sayagues, MJ; Briancin, J; Zorkovska, A; Bujnakova, Z; Kovac, J; Kovac, J; Balaz, P; Ficeriova, JJournal of Materials Science, 51 (2016) 1978-1984 DOI: 10.1007/s10853-015-9507-x

Abstract
Nanocrystalline CuInS2 particles have been synthesized from copper, indium, and sulfur powders by high-energy milling in a planetary mill in an argon atmosphere. Structural characterization of the prepared nanoparticles, including phase identification, Raman spectroscopy, specific surface area measurement, and particle size analysis were performed. The optical properties were studied using UV-Vis absorption and photoluminescence (PL) spectroscopy. The production of CuInS2 (JCPDS 027-0159) particles with a crystallite size of about 17.5-23.5 nm was confirmed by X-ray diffraction. The crystal structure has a tetragonal body-centered symmetry belonging to the I-42d space group. The Raman spectra also proved the formation of pure CuInS2 nanoparticles. TEM and HRTEM measurements revealed the presence of nanoparticles of different dimensions (10-20 nm) and their tendency to form agglomerates. The nanoparticles tend to agglomerate due to their large specific surface area. The average size of the synthesized particles was determined by photon cross-correlation spectroscopy to be in the range of 330-530 nm (bimodal size distribution). The band gap of the CuInS2 particles is 2 eV which is wider than that in bulk materials. The decrease in size leads to the blue-shift of the PL spectra. Therefore, CuInS2 nanoparticles are promising candidates for optical applications, and they have high potential in solar energy conversion.
February, 2016 · DOI: 10.1007/s10853-015-9507-x
Nanotecnología en Superficies y Plasma
Ripening and recrystallization of NaCl nanocrystals in humid conditions
Oliva-Ramirez, M; Macias-Montero, M; Borras, A; Gonzalez-Elipe, ARRSC Advances, 6 (2016) 3778-3782 DOI: 10.1039/C5RA22425J

Abstract
This study shows that Ostwald ripening, a universal mechanism responsible for the increase of crystal size during precipitation from solutions, can be meditated by ion diffusion through condensed monolayers of water that connect separated nanocrystals. In an environmental electron microscope we have observed "in situ" the time evolution of the number, shape, size and crystallographic texture of NaCl nanoparticles deposited by electron beam evaporation at oblique angles. Analysis of NaCl nanoparticles before and after water vapor condensation has evidenced that the size of nanocrystals is not the unique driving force inducing nanoparticle ripening and recrystallization, but the faceting of their crystalline habits and the amorphisation degree of the initially deposited nuclei also play important roles. These findings have implications for other crystallization and nucleation processes and can be of relevance for rock weathering and related phenomena.
February, 2016 · DOI: 10.1039/C5RA22425J
Materiales Nanoestructurados y Microestructura
Determination of the Anisotropic Elastic Properties of Rocksalt Ge2Sb2Te5 by XRD, Residual Stress, and DFT
Cecchini, R; Kohary, K; Fernandez, A; Cabibbo, M; Marmier, AJournal of Physical Chemistry C, 120 (2016) 5624-5629 DOI: 10.1021/acs.jpcc.5b09867

Abstract
The chalcogenide material Ge2Sb2Te5 is the prototype phase-change material, with widespread applications for optical media and random access memory. However, the full set of its independent elastic properties has not yet been published. In this study, we determine the elastic constants of the rocksalt Ge2Sb2Te5, experimentally by X-ray diffraction (XRD) and residual stress and computationally by density functional theory (DFT). The stiffnesses (XRD-stress/DFT) in GPa are C-11 = 41/58, C-12 = 7/8, and C-44 = 8/12, and the Zener ratio is 0.46/0.48. These values are important to understand the effect of elastic distortions and nonmelting processes on the performances of increasingly small phase change data bits.
February, 2016 · DOI: 10.1021/acs.jpcc.5b09867
Reactividad de Sólidos
Study by DSC and HRTEM of the aging strengthening of Cu-Ni-Zn-Al alloys
Dianez, MJ; Donoso, E; Criado, JM; Sayagues, MJ; Diaz, G; Olivares, LMaterials & Design, 92 (2016) 184-188 DOI: 10.1016/j.matdes.2015.12.030

Abstract
The structural changes of a Cu-12 wt.% Ni-17 wt.% Zn-1.7 wt% Al alloy as a function of the aging temperature have been studied by means of Differential Scanning Calorimetry (DSC), high resolution transmission electron microscopy (HRTEM) and hardness measurements. It has been proposed a hardening mechanism that implies the crystallization of a Ll(0) Cu2NiZn phase coherent with the matrix a phase followed, firstly, by its transformation into a Ll(2) coherent phase and, secondly, by the precipitation of this phase. It has been shown that aluminum play an important role in the precipitation hardening process because Cu2NiZn precipitates are not formed by aging a ternary Cu-Ni-Zn alloy of similar composition. It has been shown by the first time that DSC could be a powerful tool for discriminating the whole set of phase transformations undergone by alloys as a function of the annealing temperature from a single heating run.
February, 2016 · DOI: 10.1016/j.matdes.2015.12.030
Química de Superficies y Catálisis
Ru-Ni Catalyst in the Combined Dry-Steam Reforming of Methane: The Importance in the Metal Order Addition
Alvarez, MA; Centeno, MA; Odriozola, JATopics in Catalysis, 59 (2016) 303-313 DOI: 10.1007/s11244-015-0426-5

Abstract
Biogas is one of the main biomass-energy resources. Its use for syngas production with a H-2/CO ratio close to two would have huge environmental, social and economic impact in the actual energetic scenario. However, the use of dry reforming, where the two main components are transformed into syngas, does not allow the desired H-2/CO ratio. For this reason, the addition of water is proposed. The process was performed with two Ru-Ni catalysts where the metal order in the impregnation process was varied. The catalysts were prepared either by simultaneous or consecutive impregnation of the active phases and its catalytic performance in the combined dry-steam reforming of methane was tested. The catalysts were characterized by XRF, XRD, S-BET, TPR-H-2 and Raman spectroscopy. The existence of a strong Ni-Ru interaction is evidenced by Raman spectroscopy and TPR-H-2 in the sample synthesized by the simultaneous impregnation. Concerning the catalytic activity, this sample presents the highest CH4 and CO2 conversion values in the entire composition rate and the lowest amount of carbon deposits after reaction. After pulse, and reactivity tests it was concluded that the higher Ni-Ru interaction displayed by the catalyst synthesized by the simultaneous impregnation, enhances the carbon gasification.
February, 2016 · DOI: 10.1007/s11244-015-0426-5
Nanotecnología en Superficies y Plasma
Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls
Filippin, AN; Macias-Montero, M; Saghi, Z; Idigoras, J; Burdet, P; Barranco, A; Midgley, P; Anta, JA; Borras, AScientific Reports, 5 (2016) 20637 DOI: 10.1038/srep20637

Abstract
A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a post-annealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensor.
February, 2016 · DOI: 10.1038/srep20637
Nanotecnología en Superficies y Plasma
Nanostructured Ti thin films by magnetron sputtering at oblique angles
Alvarez, R; Garcia-Martin, JM; Garcia-Valenzuela, A; Macias-Montero, M; Ferrer, FJ; Santiso, J; Rico, V; Cotrino, J; Gonzalez-Elipe, AR; Palmero, AJournal of Physics D-Applied Physics, 49 (2016) 045303 DOI: 10.1088/0022-3727/49/4/045303
Abstract
The growth of Ti thin films by the magnetron sputtering technique at oblique angles and at room temperature is analysed from both experimental and theoretical points of view. Unlike other materials deposited in similar conditions, the nanostructure development of the Ti layers exhibits an anomalous behaviour when varying both the angle of incidence of the deposition flux and the deposition pressure. At low pressures, a sharp transition from compact to isolated, vertically aligned, nanocolumns is obtained when the angle of incidence surpasses a critical threshold. Remarkably, this transition also occurs when solely increasing the deposition pressure under certain conditions. By the characterization of the Ti layers, the realization of fundamental experiments and the use of a simple growth model, we demonstrate that surface mobilization processes associated to a highly directed momentum distribution and the relatively high kinetic energy of sputtered atoms are responsible for this behaviour.
February, 2016 · DOI: 10.1088/0022-3727/49/4/045303
Materiales Ópticos Multifuncionales
Efficient bifacial dye-sensitized solar cells through disorder by design
Miranda-Munoz, JM; Carretero-Palacios, S; Jimenez-Solano, A; Li, YL; Lozano, G; Miguez, HJournal of Materials Chemistry A, 4 (2016) 1953-1961 DOI: 10.1039/C5TA10091G

Abstract
Herein we realize an optical design that optimizes the performance of bifacial solar cells without modifying any of the usually employed components. In order to do so, dielectric scatterers of controlled size and shape have been successfully integrated in the working electrodes of dye-sensitized solar cells (DSSCs), resulting in bifacial devices of outstanding performance. Power conversion efficiencies (PCEs) as high as 6.7% and 5.4% have been attained under front and rear illumination, respectively, which represent a 25% and a 33% PCE enhancement with respect to an 8 μm-thick standard solar cell electrode using platinum as the catalytic material. The remarkable bifacial character of our approach is demonstrated by the high rear/front efficiency ratio attained, around 80%, which is among the largest reported for this sort of device. The proposed optimized design is based on a Monte Carlo approach in which the multiple scattering of light within the cell is fully accounted for. We identified that the spherical shape of the scatterers is the key parameter controlling the angular distribution of the scattering, the most efficient devices being those in which the inclusions provide a narrow forward-oriented angular distribution of the scattered light.
January, 2016 · DOI: 10.1039/C5TA10091G
Reactividad de Sólidos
Kinetics of high-temperature oxidation of (Ti,Ta)(C,N)-based cermets
Chicardi, E; Cordoba, JM; Gotor, FJCorrosion Science, 102 (2016) 168-177 DOI: 10.1016/j.corsci.2015.10.006

Abstract
The kinetics of the high-temperature oxidation of titanium–tantalum carbonitride-based cermets with different Ti/Ta ratios was studied. Isothermal oxidation tests were conducted under static air for 48 h at temperatures between 700 °C and 1200 °C. The oxidation satisfied the parabolic kinetics, characteristic of the existence of a protective oxide layer. The apparent activation energy suggests the rate-controlling process during oxidation is the simultaneous inward and outward diffusion of oxygen and titanium, respectively, through the formed protective layer, consisting mainly of a rutile phase. A higher Ta(V) content in the rutile decreased the oxygen diffusivity due to the reduction of oxygen vacancy concentration.
January, 2016 · DOI: 10.1016/j.corsci.2015.10.006
Nanotecnología en Superficies y Plasma
Quantitative analysis of Ni 2p photoemission in NiO and Ni diluted in a SiO2 matrix
Pauly, N; Yubero, F; Garcia-Garcia, FJ; Tougaard, SSurface Science, 644 (2016) 46-52 DOI: 10.1016/j.susc.2015.09.012

Abstract
In X-ray excited photoelectron emission (XPS), besides the initial excitation process, the shape and intensity of photoelectron peaks are strongly affected by extrinsic excitations due to electron transport out of the surface (including bulk and surface effects) and to intrinsic excitations due to the sudden creation of the static core hole. To make an accurate quantitative interpretation of features observed in XPS, these effects must be included in the theoretical description of the emitted photoelectron spectra. It was previously shown [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17] that these three effects can be calculated by means of the QUEELS-XPS software (Quantitative analysis of Electron Energy Losses at Surfaces for XPS) in terms of effective energy-differential inelastic electron scattering cross-sections. The only input needed to calculate these cross-sections is the energy loss function of the media which is determined from analysis of Reflection Electron Energy Loss Spectra (REELS). The full XPS spectrum is then modeled by convoluting this energy loss cross-section with the primary excitation spectrum that accounts for all effects which are part of the initial photo-excitation process, i.e. lifetime broadening, spin-orbit coupling, and multiplet splitting. In this paper we apply the previously presented procedure to the study of Ni 2p photoemission in NiO and Ni diluted in a SiO2 matrix (Ni:SiO2), samples being prepared by reactive magnetron sputtering at room temperature. We observe a significant difference between the corresponding Ni 2p primary excitation spectra. The procedure allows quantifying the relative intensity of the c3d(9)L, c3d(10)L(2), and c3d(8) final states contributing to the Ni 2p photoemission spectra of the Ni2+ species in the oxide matrices. Especially, the intensity ratio in NiO between the non-local and local contributions to the 3d(9)L configuration is determined to be 2.5. Moreover the relative intensity ratio of the c3d(9)L/c3d(10)L(2)/c3d(8) configurations is found to be 1.0/0.83/0.11 for both the NiO and Ni:SiO2 samples.
January, 2016 · DOI: 10.1016/j.susc.2015.09.012
Materiales de Diseño para la Energía y Medioambiente
Thermal conductivity of partially graphitized biocarbon obtained by carbonization of medium-density fiberboard in the presence of a Ni-based catalyst
Orlova, TS; Parfen'eva, LS; Smirnov, BI; Gutierrez-Pardo, A; Ramirez-Rico, JPhysics of the Solid State, 58 (2016) 208-214 DOI: 10.1134/S1063783416010236
Abstract
The thermal conductivity k and resistivity rho of biocarbon matrices, prepared by carbonizing medium-density fiberboard at T (carb) = 850 and 1500A degrees C in the presence of a Ni-based catalyst (samples MDF-C( Ni)) and without a catalyst (samples MDF-C), have been measured for the first time in the temperature range of 5-300 K. X-ray diffraction analysis has revealed that the bulk graphite phase arises only at T (carb) = 1500A degrees C. It has been shown that the temperature dependences of the thermal conductivity of samples MDFC- 850 and MDF-C-850(Ni) in the range of 80-300 K are to each other and follow the law of k(T) similar to T (1.65), but the use of the Ni-catalyst leads to an increase in the thermal conductivity by a factor of approximately 1.5, due to the formation of a greater fraction of the nanocrystalline phase in the presence of the Ni-catalyst at T (carb) = 850A degrees C. In biocarbon MDF-C-1500 prepared without a catalyst, the dependence is k(T) similar to T (1.65), and it is controlled by the nanocrystalline phase. In MDF-C-1500(Ni), the bulk graphite phase formed increases the thermal conductivity by a factor of 1.5-2 compared to the thermal conductivity of MDF-C-1500 in the entire temperature range of 5-300 K; k(T = 300 K) reaches the values of similar to 10 W m(-1) K-1, characteristic of biocarbon obtained without a catalyst only at high temperatures of T (carb) = 2400A degrees C. It has been shown that MDF-C-1500(Ni) in the temperature range of 40aEuro'300 K is characterized by the dependence, k(T) similar to T (1.3), which can be described in terms of the model of partially graphitized biocarbon as a composite of an amorphous matrix with spherical inclusions of the graphite phase.
January, 2016 · DOI: 10.1134/S1063783416010236
Materiales de Diseño para la Energía y Medioambiente
Influence of temperature and time on the Eu3+ reaction with synthetic Na-Mica-n (n=2 and 4)
Garcia-Jimenez, MJ; Cota, A; Osuna, FJ; Pavon, E; Alba, MDChemical Engineering Journal, 284 (2016) 1174-1183 DOI: 10.1016/j.cej.2015.09.077

Abstract
Bentonite is accepted as the best clay material for the engineered barrier of Deep Geological Repositories (DGRs). The performance of clay as the main component of the engineered barrier in the DGR has been intensively studied and the structure of the selected clay mineral play a crucial role. In this sense, a new family of synthetic swelling silicates, Na-Mica-n, with tuned layer charge (n) values between 2.0 and 4.0 per unit cell has recently been synthesized and a general synthetic method has been reported. These swelling high-charge micas could be highly valuable for the decontamination of harmful cations. The ability of these micas to immobilize Eu3+ under subcritical conditions has been probed. The adsorption was in both non-specific sites (cation exchange mechanism) and specific sites (chemical reaction or surface defects adsorption). Moreover, its adsorption capacity, under the same conditions is higher than in saponite and far superior to the bentonites.
January, 2016 · DOI: 10.1016/j.cej.2015.09.077
Nanotecnología en Superficies y Plasma
Application of Prussian Blue electrodes for amperometric detection of free chlorine in water samples using Flow Injection Analysis
Salazar, P; Martin, M; Gonzalez-Mora, JL; Gonzalez-Elipe, ARTalanta, 146 (2016) 410-416 DOI: 10.1016/j.talanta.2015.08.072

Abstract
The performance for free chlorine detection of surfactant-modified Prussian Blue screen printed carbon electrodes (SPCEs/PB-BZT) have been assessed by cyclic voltammetry and constant potential amperometry. The characterization of SPCEs/PB-BZT by X-ray photoemission, Raman and infrared spectroscopies confirmed the correct electrodeposition of the surfactant-modified PB film. These electrodes were incorporated in a Flow Injection device and the optimal working conditions determined as a function of experimental variables such as detection potential, electrolyte concentration or flow-rate. The sensor presented a linear response in the range 0–3 ppm free chlorine, with a sensitivity of 16.2 μA ppm−1 cm−2. The limit of detection (LOD) (S/N=3.3) and the limit of quantification (S/N=10) amounted to 8.25 and 24.6 ppb, respectively, adequate for controlling tap and drinking waters. To demonstrate the feasibility of using this free chlorine sensor for real applications possible interferences such as nitrate, nitrite and sulfate ions were successfully tested and discarded. Real free chlorine analysis was carried out in spiked tap water samples and commercial bleaches.
January, 2016 · DOI: 10.1016/j.talanta.2015.08.072
Nanotecnología en Superficies y Plasma - Tribología y Protección de Superficies
Highly Porous ZnO Thin Films and 1D Nanostructures by Remote Plasma Processing of Zn-Phthalocyanine
Alcaire, M; Filippin, AN; Macias-Montero, M; Sanchez-Valencia, JR; Rojas, TC; Mora-Boza, A; Lopez-Santos, C; Espinos, JP; Barranco, A; Borras, APlasma Processes and Polymers, 13 (2016) 287-297 DOI: 10.1002/ppap.201500133

Abstract
In this paper the fabrication of highly porous 1D nanostructures by a vacuum and plasma etching combined protocol is presented. Zn-phthalocyanine (ZnPc) is utilized as a solid precursor to form the ZnO. First the ZnPc is sublimated in low argon pressure. Depending on the substrate temperature and microstructure, polycrystalline films or single crystal ZnPc nanowires are grown. These starting materials are then subjected to a remote plasma oxidizing treatment. Experimental parameters such as substrate position, plasma power, treatment duration, and substrate temperature determine the microstructure and properties of the final ZnO nanostructures. The article gathers an in depth study of the obtained porous nanostructured films following scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), UV-Vis transmittance, and fluorescence spectroscopies.
January, 2016 · DOI: 10.1002/ppap.201500133
Materiales Coloidales
Ligand-Free Synthesis of Tunable Size Ln:BaGdF5 (Ln = Eu3+ and Nd3+) Nanoparticles: Luminescence, Magnetic Properties, and Biocompatibility
Becerro, AI; Gonzalez-Mancebo, D; Cantelar, E; Cusso, F; Stepien, G; de la Fuente, JM; Ocana, MLangmuir, 32 (2016) 411-420 DOI: 10.1021/acs.langmuir.5b03837

Abstract
Bifunctional and highly uniform Ln:BaGdF5 (Ln = Eu3+ and Nd3+) nanoparticles have been successfully synthesized using a solvothermal method consisting of the aging at 120 degrees C of a glycerol solution containing the corresponding Lanthanide acetylacetonates and butylmethylimidazolium tetrafluoroborate. The absence of any surfactant in the synthesis process rendered hydrophilic nanospheres (with tunable diameter from 45 nm 85 nm, depending on the cations concentration of the starting solution) which are suitable for bioapplications. The particles are bifunctional because they showed both optical and magnetic properties due to the presence of the optically active lanthanides (Eu3+ in the visible and Nd3+ in the NIR regions of the electromagnetic spectrum) and the paramagnetic gadolinium ion, respectively. The luminescence decay curves of the nanospheres doped with different amounts of Eu3+ and Nd3+ have been recorded in order to determine the optimum dopant concentration in each case, which turned out to be 5% Eu3+ and 0.5% Nd3+. Likewise, proton relaxation times were measured at 1.5 T in water suspensions of the optimum particles found in the luminescence study. The values obtained suggested that both kinds of particles could be used as positive contrast agents for MRI. Finally, it was demonstrated that both the 5% Eu3+ and 0.5% Nd3+-doped BaGdF5 nanospheres showed negligible cytotoxicity for VERO cells for concentrations up to 0.25 mg mL(-1).
January, 2016 · DOI: 10.1021/acs.langmuir.5b03837
Materiales Coloidales
Deposition of silica protected luminescent layers of Eu:GdVO4 nanoparticles assisted by atmospheric pressure plasma jet
Moretti, E; Pizzol, G; Fantin, M; Enrichi, F; Scopece, P; Nunez, NO; Ocana, M; Benedetti, A; Polizzi, SThin Solid Films, 598 (2016) 88-94 DOI: 10.1016/j.tsf.2015.11.061

Abstract
Eu:GdVO4 nanophosphors with an average size of 60 nm, synthesized by a facile solvothermal method, were deposited on monocrystalline silicon wafers by a spray-coating technique with artworks anti-counterfeiting applications in mind. Atmospheric pressure plasma jet (APPJ) was used to deposit a silica-based layer on top of the nanometric luminescent layer, in order to improve its adhesion to the substrate and to protect it from the environment. The nanophosphors were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Coating composition was investigated by Fourier transform infrared spectroscopy (FT-IR) and its morphology was characterized by scanning electron microscopy (FEG-SEM). The film thickness was evaluated by means of ellipsometry and adhesion was estimated by a peeling test. Luminescent properties of the nanophosphors deposited and fixed on silicon wafers were also measured. The whole layer resulted well-adhered to the silicon substrate, transparent and undetectable in the presence of visible light, but easily activated by UV light source.
January, 2016 · DOI: 10.1016/j.tsf.2015.11.061
Materiales Nanoestructurados y Microestructura
Disorder-order phase transformation in a fluorite-related oxide thin film: In-situ X-ray diffraction and modelling of the residual stress effects
Gaboriaud, RJ; Paumier, F; Lacroix, BThin Solid Films, 601 (2016) 84-88 DOI: 10.1016/j.tsf.2015.08.030

Abstract
This work is focused on the transformation of the disordered fluorite cubic-F phase to the ordered cubic-C bixbyite phase, induced by isothermal annealing as a function of the residual stresses resulting from different concentrations of microstructural defects in the yttrium oxide, Y2O3.
This transformation was studied using in-situ X-ray diffraction and was modelled using Kolmogorov-Johnson-Mehl-Avrami (KJMA) analysis. The degree of the disorder of the oxygen network was associated with the residual stress, which was a key parameter for the stability and the kinetics of the transition of the different phases that were present in the thin oxide film. When the degree of disorder/residual stress level is high, this transition, which occurs at a rather low temperature (300 degrees C), is interpreted as a transformation of phases that occurs by a complete recrystallization via the nucleation and growth of a new cubic-C structure. Using the KJMA model, we determined the activation energy of the transformation process, which indicates that this transition occurs via a one-dimensional diffusion process. Thus, we present the analysis and modelling of the stress state. When the disorder/residual stress level was low, a transition to the quasi-perfect ordered cubic-C structure of the yttrium oxide appeared at a rather high temperature (800 degrees C), which is interpreted as a classic recovery mechanism of the cubic-C structure.
January, 2016 · DOI: 10.1016/j.tsf.2015.08.030
Materiales Coloidales
Gold-Based Nanomaterials for Applications in Nanomedicine
Ashraf, S; Pelaz, B; del Pino, P; Carril, M; Escudero, A; Parak, WJ; Soliman, MG; Zhang, Q; Carrillo-Carrion, CLight-Responsive Nanostructured Systems for Applications in Nanomedicine, 370 (2016) 169-202 DOI: http://link.springer.com/chapter/10.1007%2F978-3-319-22942-3_6

Abstract
In this review, an overview of the current state-of-the-art of gold-based nanomaterials (Au NPs) in medical applications is given. The unique properties of Au NPs, such as their tunable size, shape, and surface characteristics, optical properties, biocompatibility, low cytotoxicity, high stability, and multifunctionality potential, among others, make them highly attractive in many aspects of medicine. First, the preparation methods for various Au NPs including functionalization strategies for selective targeting are summarized. Second, recent progresses on their applications, ranging from the diagnostics to therapeutics are highlighted. Finally, the rapidly growing and promising field of gold-based theranostic nano-platforms is discussed. Considering the great body of existing information and the high speed of its renewal, we chose in this review to generalize the data that have been accumulated during the past few years for the most promising directions in the use of Au NPs in current medical research.
January, 2016 · DOI: http://link.springer.com/chapter/10.1007%2F978-3-319-22942-3_6
Materiales Nanoestructurados y Microestructura
Investigation of a Pt containing washcoat on SiC foam for hydrogen combustion applications
Fernandez, A; Arzac, GM; Vogt, UF; Hosoglu, F; Borgschulte, A; de Haro, MCJ; Montes, O; Zuttel, AApplied Catalysis B: Environmental, 180 (2016) 336-343 DOI: 10.1016/j.apcatb.2015.06.040

Abstract
A commercial Pt based washcoat, used for catalytic methane combustion, was studied supported on a commercial SiC foam as catalytic material (Pt/SiC) for catalytic hydrogen combustion (CHC). Structural and chemical characterization was performed using Electron Microscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The reaction was monitored following water concentration by Fourier Transform Infrared spectra (FTIR). The FTIR method was compared with H2 detection by Gas Cromatography (GC) and has shown to be adequate to study the kinetics of the CHC reaction in steady state under our experimental conditions (very lean 1% (v/v) H2/air mixtures). The catalyst is composed of 5–20 nm disperse Pt nanoparticles decorating a mixture of high surface area Al2O3 and small amounts of ceria supported on the SiC foam which also contains alumina as binder. The Pt/SiC catalytic material has demonstrated to be active enough to start up the reaction in a few seconds at room temperature. The material has been able to convert at least 18.5 Lhydrogen min−1 gPt−1 at room temperature in conditions of excess of catalyst. The Pt/SiC material was studied after use using XPS and no significant changes on Pt oxidation states were found. The material was characterized from a kinetic point of view. From the conversion-temperature plot a T50(temperature for 50% conversion) of 34 °C was obtained. Activation energy measured in our conditions was 35 ± 1 kJ mol−1.
January, 2016 · DOI: 10.1016/j.apcatb.2015.06.040
Reactividad de Sólidos
The Calcium-Looping technology for CO2 capture: On the important roles of energy integration and sorbent behavior
Perejon, A; Romeo, LM; Lara, Y; Lisbona, P; Martinez, A; Valverde, JMApplied Energy, 162 (2016) 787-807 DOI: 10.1016/j.apenergy.2015.10.121

Abstract
The Calcium Looping (CaL) technology, based on the multicyclic carbonation/calcination of CaO in gas-solid fluidized bed reactors at high temperature, has emerged in the last years as a potentially low cost technology for CO2 capture. In this manuscript a critical review is made on the important roles of energy integration and sorbent behavior in the process efficiency. Firstly, the strategies proposed to reduce the energy demand by internal integration are discussed as well as process modifications aimed at optimizing the overall efficiency by means of external integration. The most important benefit of the high temperature CaL cycles is the possibility of using high temperature streams that could reduce significantly the energy penalty associated to CO2 capture. The application of the CaL technology in precombustion capture systems and energy integration, and the coupling of the CaL technology with other industrial processes are also described. In particular, the CaL technology has a significant potential to be a feasible CO2 capture system for cement plants. A precise knowledge of the multicyclic CO2 capture behavior of the sorbent at the CaL conditions to be expected in practice is of great relevance in order to predict a realistic capture efficiency and energy penalty from process simulations. The second part of this manuscript will be devoted to this issue. Particular emphasis is put on the behavior of natural limestone and dolomite, which would be the only practical choices for the technology to meet its main goal of reducing CO2 capture costs. Under CaL calcination conditions for CO2 capture (necessarily implying high CO2 concentration in the calciner), dolomite seems to be a better alternative to limestone as CaO precursor. The proposed techniques of recarbonation and thermal/mechanical pretreatments to reactivate the sorbent and accelerate calcination will be the final subjects of this review.
January, 2016 · DOI: 10.1016/j.apenergy.2015.10.121
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