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Catalytic performance of cobalt supported onto APTES functionalized TiO2 for Fischer-Tropsch reaction

Platero, F; Caballero, A; Colon, G
Fuel, 340 (2023) 127528
Materiales y Procesos Catalíticos de Interés Ambiental y Energético


Cobalt supported TiO2 catalysts have been prepared by wet-impregnation and by immobilization over APTES (3-aminopropyl triethoxysilane) grafted TiO2. Impregnated system showed better catalytic performance after reduction at 260 degrees C but significant deactivation is observed. On the contrary, functionalized catalyst showed better catalytic performance after reduction at 400 degrees C with notable stability. We have stated from CO-DRIFT operando analysis that impregnated system is strongly affected by negative SMSI (strong metal-support inter-action) upon reduction at higher temperature. While immobilization on APTES hinders the loss of metal active sites. The study of spent catalysts denotes that Co is redispersed in the impregnated catalyst while functionalized trends to form agglomerates.

Mayo, 2023 | DOI: 10.1016/j.fuel.2023.127528

Electrical performance of orthotropic and isotropic 3YTZP composites with graphene fillers

Lopez-Pernia, C; Muñoz-Ferreiro, C; Moriche, R; Morales-Rodriguez, A; Gallardo-Lopez, A; Poyato, R
Journal of The European Ceramic Society, 43 (2023) 1605-1612
Reactividad de Sólidos


3 mol% yttria tetragonal zirconia polycrystal (3YTZP) composites with orthotropic or isotropic microstructures were obtained incorporating few layer graphene (FLG) or exfoliated graphene nanoplatelets (e-GNP) as fillers. Electrical conductivity was studied in a wide range of contents in two configurations: perpendicular (sigma(perpendicular to)) and parallel (sigma(//)) to the pressing axis during spark plasma sintering (SPS). Isotropic e-GNP composites presented excellent electrical conductivity for high e-GNP contents (sigma(perpendicular to)similar to 3200 S/m and sigma(//) similar to 1900 S/m for 20 vol% e-GNP), consequence of their misoriented distribution throughout the matrix. Optimum electrical performance was achieved in the highly anisotropic FLG composites, with high electrical conductivity for low contents (sigma(perpendicular to) similar to 680 S/m for 5 vol%), percolation threshold below 2.5 vol% FLG and outstanding electrical conductivity for high contents (sigma(perpendicular to) similar to 4000 S/m for 20 vol%), result of the high aspect ratio and low thickness of FLG.

Abril, 2023 | DOI: 10.1016/j.jeurceramsoc.2022.11.068

Large-scale oxygen-enriched air (OEA) production from polymeric membranes for partial oxycombustion processes

Garcia-Luna, S; Ortiz, C; Chacartegui, R; Perez-Maqueda, LA
Energy, 268 (2023) 126697
Reactividad de Sólidos


Partial oxycombustion using Oxygen-Enriched Air (OEA), produced by air-gas separation with polymeric membranes, combined synergistically with CO2 capture technologies, can reduce the overall energy cost of CO2 capture, and it is a potential alternative to conventional CO2 capture technologies. An exhaustive review of polymeric membranes for this application is presented. The best membranes showed permeability values in the 450-25,100 barrer and selectivities higher than 3.6 for large-scale operations. These membranes can produce OEA with oxygen molar concentrations of up to 40% for retrofitting large-scale power plants (similar to 500 MWe) with partial oxycombustion. For OEA production, the polymeric membrane system is more efficient than cryogenic distillation since the specific power consumption of the former is 35.17 kWh/ton OEA. In comparison, that of the latter is 49.57 kWh/ton OEA. This work proposes that the OEA produced by the membranes feed a partial oxycombustion process integrated with calcium looping within a hybrid CO2 capture system. The power con-sumption of the hybrid CO2 capture system proposed here is 29.05% lower than in the case OEA is produced from cryogenic distillation, which justifies the potential interest in using polymeric membranes for OEA production.

Abril, 2023 | DOI: 10.1016/

Effect of Mo and W interlayers on microstructure and mechanical properties of Si3N4-nickel-base superalloy joints

Singh, M; Fernandez, JM; Asthana, R; Ramirez-Rico, J; Valera-Feria, FM
International Journal of Applied Ceramic Technology (2022)
Materiales de Diseño para la Energía y Medioambiente


Si3N4/nickel-base superalloy (Inconel-625) and Si3N4/Si3N4 joints with refractory metal (W and Mo) interlayers were vacuum brazed using a Ti-active braze Cu-ABA (92.75Cu-3Si-2Al-2.25Ti) at 1317 K for 30 min with the following interlayered arrangements: Si3N4/Mo/W/Inconel and Si3N4/Mo/W/Si3N4. The joints exhibited Ti segregation at the Si3N4/Cu-ABA interface, elemental interdiffusion across the joint interfaces, and sound metallurgical bonding. Knoop microhardness profiles revealed hardness gradients across the joints that mimicked the interlayered arrangement. The compressive shear strength of Si3N4/Si3N4 joints both with and without W and Mo layers was similar to 142 MPa but the strength of Si3N4/Inconel joints increased from similar to 9 MPa for directly bonded joints without interlayers to 53.5 MPa for joints with Mo and W interlayers.

Marzo, 2023 | DOI: 10.1111/ijac.14266

Oxidation and coordination states assumed by transition metal dopants in an invert ultrabasic silicate glass

Zandona, A; Castaing, V; Shames, AI; Helsch, G; Deubener, J; Becerro, AI; Allix, M; Goldstein, A
Journal of Non-Crystalline Solids, 603 (2023) 122094
Materiales Ópticos Multifuncionales - Materiales Coloidales


An ultrabasic invert silicate glass (46SiO2.11Na2O.21CaO.22BaO, optical basicity index equal to 0.71) was synthesized (O2 atmosphere) and used as host for various transition metal dopants. Optical absorption, emission and electron paramagnetic spectroscopies were used to characterize oxidation and coordination states. Some of the dopants displayed only their maximal oxidation state (Ti4+, V5+, Cr6+, Mo6+ and W6+). Others exhibited mixed valences: (i) Mn3+ was the dominant species, alongside Mn2+ and Mn5+; (ii) stable Fe3+ prevailed, although some Fe2+ was preliminarily suggested by the absorption spectrum; (iii) Co3+ probably accompanied the dominant Co2+ tetrahedral oxide complex; (iv) like in "conventional" silicate glasses, only Ni2+ was detected, though simultaneously located in tetrahedral and octahedral sites (somewhat distorted); (v) Cu+ was surprisingly identified alongside the expected 6-fold coordinated Cu2+. Drastic reduction of the oxygen content in the melting atmosphere led to conversion of Cr6+ to Cr3+, despite the extreme basicity of the host.

Marzo, 2023 | DOI: 10.1016/j.jnoncrysol.2022.122094

Low CO2 hydrogen streams production from formic acid through control of the reaction pH

Santos, JL; Lopez, ER; Ivanova, S; Monzon, A; Centeno, MA; Odriozola, JA
Chemical Engineering Journal, 455 (2023) 140645
Química de Superficies y Catálisis


There are multiple factors that influence the catalyst performance in the reaction of formic acid dehydrogena-tion: the nature of catalyst and/or support, the used solvent and reaction variables such as temperature, time, formic acid concentration, presence/absence of formates and pH of the solution. This work evaluates a series of important parameters like the influence of the pH by itself, the influence of the nature of used alkali agents and the effect of direct formate addition as reactive on hydrogen production via formic acid dehydrogenation over a commercially available catalyst. The catalytic performance appears to depend on the ionic radius of the cations of the used base which reflects consequently on the hydrogen selectivity. The best base to be used must have lower hydrated cationic radii and a starting pH around 4 to achieve important hydrogen selectivity for medium term formic acid conversion.

Febrero, 2023 | DOI: 10.1016/j.cej.2022.140645

Bio-based lacquers from industrially processed tomato pomace for sustainable metal food packaging

Benitez, JJ; Ramirez-Pozo, MC; Duran-Barrantes, MM; Heredia, A; Tedeschi, G; Ceseracciu, L; Guzman-Puyol, S; Marrero-López, D; Becci, A; Amato, A; Heredia-Guerrero, JA
Journal of Cleaner Production, 386 (2023) 1356836
Materiales de Diseño para la Energía y Medioambiente


Bio-based lacquers prepared from an underutilized tomato processing residue such as pomace have been investigated as sustainable alternatives to bisphenol A (BPA)-based coatings for metal food packaging. The fabrication methodology consisted of a two-step process: spray-coating of a paste of the lipid fraction of tomato pomace with a mixture ethanol:H2O (3:1, v:v) on common metal substrates, used for food canning, such as aluminum (Al), chromium-coated tin-free steel (TFS), and electrochemically tin-plated steel (ETP), followed by the self melt-polycondensation of such lipid fraction. The polymerization reaction was conducted at 200 degrees C for different times (10, 20, 30, 40, 50, and 60 min) and was monitored by specular infrared spectroscopy, resulting in maximum degrees of esterification of-92% for Al and-85% for TFS and ETP substrates. The anticorrosion performance of the coatings was studied by electrochemical impedance spectroscopy at different immersion times (time intervals of 2-5 h during an overall stability test up to 170 h) in an aqueous solution of 1 wt% NaCl. The degree of polymerization and the physical properties of the coatings showed a strong dependence on the metal substrate used. In general, the best results were found for tomato pomace-based lacquers applied on aluminum, achieving higher mechanical strength (critical load of 1739 +/- 198 mN for Al, 1078 +/- 31 mN for ETP, and 852 +/- 206 mN for TFS), hydrophobicity (water contact angle-95 degrees for Al,-91 degrees for ETP, and-88 degrees for TFS), and improved anticorrosion performance (coating resistance of 0.7 M omega cm2 after 170 h of immersion for Al, 0.7 M omega cm2 after 70 h of immersion for TFS, and negligible coating resistance for ETP). In view of the technical innovation proposed in the present paper, the estimation of the environmental sustainability of the process has been considered relevant to fit the circular economy target. For this purpose, a life cycle analysis (LCA) was applied to the overall process, revealing multiple advantages for both the environment and human health.

Febrero, 2023 | DOI: 10.1016/j.jclepro.2022.135836

Determination of the activation energy under isothermal conditions: revisited

Arcenegui-Troya, J; Sanchez-Jimenez, PE; Perejon, A; Perez-Maqueda, LA
Journal of Thermal Analysis and Calorimetry, 148 (2023) 1679-1686
Reactividad de Sólidos


The kinetic analysis of solid-state processes aims at obtaining fundamental information that can be used for predicting the time evolution of a process within a wide range of conditions. It is an extended belief that the determination of the kinetic parameters from the analysis of curves recorded under isothermal conditions is strongly conditioned by the kinetic model used to fit the experimental data. Thus, much effort is devoted to finding the model that truly describes a process in order to calculate the kinetic parameters with accuracy. In this work, we demonstrate that the value of activation energy determined from kinetic analysis of isothermal curves is independent of the kinetic model used to fit the experimental data and, taking advantage of the underlying reason for this, a method for determining the activation energy with two isothermal curves is proposed.

Febrero, 2023 | DOI: 10.1007/s10973-022-11728-3

Flexible NiRu Systems for CO2 Methanation: From Efficient Catalysts to Advanced Dual-Function Materials

Merkouri, LP; Martin-Espejo, JL; Bobadilla, LF; Odriozola, JA; Duyar, MS; Reina, TR
Nanomaterials, 13 (2023) 506
Química de Superficies y Catálisis


CO2 emissions in the atmosphere have been increasing rapidly in recent years, causing global warming. CO2 methanation reaction is deemed to be a way to combat these emissions by converting CO2 into synthetic natural gas, i.e., CH4. NiRu/CeAl and NiRu/CeZr both demonstrated favourable activity for CO2 methanation, with NiRu/CeAl approaching equilibrium conversion at 350 degrees C with 100% CH4 selectivity. Its stability under high space velocity (400 L center dot g(-1)center dot h(-1)) was also commendable. By adding an adsorbent, potassium, the CO2 adsorption capability of NiRu/CeAl was boosted, allowing it to function as a dual-function material (DFM) for integrated CO2 capture and utilisation, producing 0.264 mol of CH4/kg of sample from captured CO2. Furthermore, time-resolved operando DRIFTS-MS measurements were performed to gain insights into the process mechanism. The obtained results demonstrate that CO2 was captured on basic sites and was also dissociated on metallic sites in such a way that during the reduction step, methane was produced by two different pathways. This study reveals that by adding an adsorbent to the formulation of an effective NiRu methanation catalyst, advanced dual-function materials can be designed.

Febrero, 2023 | DOI: 10.3390/nano13030506

Improved stability of design clay minerals at high temperature: A comparison study with natural ones

Osuna, FJ; Chaparro, JR; Pavon, E; Alba, MD
Ceramics International, 49 (2023) 5279-5291
Materiales de Diseño para la Energía y Medioambiente


Clay minerals are ceramics materials that are involved in a wide range of economic uses. But, their structure and composition are modified by heating and, consequently, compromise their final applications. The actual tem-peratures at which changes occur vary greatly from one group to another group and even for different specimens within a given group. The aim of this research has been to evaluate the thermal behaviour of a set of design swelling micas, Na-Mica -n (Mn) and compare them with a set of natural smectites. All samples were heated in the range 200 degrees C to 1000 degrees C; afterwards, they were rehydrated thorough water suspension (0.4% wt). The results have shown that swelling micas have better property of hydration/dehydration than natural clay minerals and those with higher layer charge exhibited higher rehydration ability and dehydration temperature.

Febrero, 2023 | DOI: 10.1016/j.ceramint.2022.10.046

Collective plasmonic resonances enhance the photoluminescence of rare-earth nanocrystal films processed by ultrafast annealing

Cabello-Olmo, E; Higashino, M; Murai, S; Tanaka, K; Lozano, G; Miguez, H
Chemical Communications, 59 (2023) 1289-1292
Materiales Ópticos Multifuncionales


Herein, we demonstrate that rapid thermal annealing allows achieving close-to-one photoluminescence quantum yield while preserving the transparency of rare-earth nanocrystal films, which further enables their integration with nanophotonics. The combination with periodic arrays of aluminum nanodisks that support collective plasmonic resonances leads to enhanced directional emission.

Enero, 2023 | DOI: 10.1039/d2cc04779a

Highly Nonstoichiometric YAG Ceramics with Modified Luminescence Properties

Cao, WW; Becerro, AI; Castaing, V; Fang, X; Florian, P; Fayon, F; Zanghi, D; Veron, E; Zandona, A; Genevois, C; Pitcher, MJ; Allix, M
Advanced Functional Materials
Materiales Ópticos Multifuncionales - Materiales Coloidales


Y3Al5O12 (YAG) is a widely used phosphor host. Its optical properties are controlled by chemical substitution at its YO8 or AlO6/AlO4 sublattices, with emission wavelengths defined by rare-earth and transition-metal dopants that have been explored extensively. Nonstoichiometric compositions Y3+xAl5-xO12 (x not equal 0) may offer a route to new emission wavelengths by distributing dopants over two or more sublattices simultaneously, producing new local coordination environments for the activator ions. However, YAG typically behaves as a line phase, and such compositions are therefore challenging to synthesize. Here, a series of highly nonstoichiometric Y3+xAl5-xO12 with 0 <= x <= 0.40 is reported, corresponding to <= 20% of the AlO6 sublattice substituted by Y3+, synthesized by advanced melt-quenching techniques. This impacts the up-conversion luminescence of Yb3+/Er3+-doped systems, whose yellow-green emission differs from the red-orange emission of their stoichiometric counterparts. In contrast, the YAG:Ce3+ system has a different structural response to nonstoichiometry and its down-conversion emission is only weakly affected. Analogous highly nonstoichiometric systems should be obtainable for a range of garnet materials, demonstrated here by the synthesis of Gd3.2Al4.8O12 and Gd3.2Ga4.8O12. This opens pathways to property tuning by control of host stoichiometry, and the prospect of improved performance or new applications for garnet-type materials.

Enero, 2023 | DOI: 10.1002/adfm.202213418

Responsive Optical Materials Based on Ligand-Free Perovskite Quantum Dots Embedded in Mesoporous Scaffolds

Romero-Perez, C; Zanetta, A; Fernandez-Delgado, N; Herrera-Collado, M; Hernandez-Saz, J; Molina, SI; Calio, L; Calvo, ME; Miguez, H
ACS Applied Materials & Interfaces 15 (2023) 1808-1816
Materiales Ópticos Multifuncionales


Herein we show that dispersing inorganic cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) in optical quality films, possessing an accessible and controlled pore size distribution, gives rise to fluorescent materials with a controlled and highly sensi t i v e response to ambient changes. A scaffold-based synthesis approach is employed to obtain ligand-free QDs, whose pristine surface endows them with high sensit i v i t y to the presence of different vapors in their vici n i t y . At the same time, the void network of the host offers a means to gradually expose the embedded QDs to such vapors. Under these conditions, the luminescent response of the QDs is mediated by the mesostructure of the matri x , which determines the rate at which vapor molecules will adsorb onto the pore walls and, eventually, condensate, filling the void space. With luminescence quantum yields as high as 60%, scaffold-supported ligand-free perovskite nanocrystals display intense photoemission signals over the whole process, as well as high photo-and chemical stabi l i t y , which allows illuminating them for long periods of time and recovering the original response upon desorption of the condensed phase. The results herein presented open a new route to explore the application of perovskite QD-based materials in sensing.

Enero, 2023 | DOI: 10.1021/acsami.2c16867

New Types and Dosages for the Manufacture of Low-Energy Cements from Raw Materials and Industrial Waste under the Principles of the Circular Economy and Low-Carbon Economy

Martinez-Martinez, S; Perez-Villarejo, L; Eliche-Quesada, D; Sanchez-Soto, PJ
Materials, 16 (2023) 802
Materiales Avanzados


The cement manufacturing industry is one of the main greenhouse gas emission producers and also consumes a large quantity of raw materials. It is essential to reduce these emissions in order to comply with the Paris Agreement and the principles of the circular economy. The objective of this research was to develop different types of cement clinker blends using industrial waste and innovative design to produce low-energy cement. Several types of waste have been studied as alternative raw materials. Their main characteristics have been analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD), Attenuated total reflectance Fourier trans-form infrared spectroscopy (ATR-FTIR), thermal analysis (TG-DTG-DSC) and scanning electron microscopy and energy dispersive X-ray spectroscopy analysis (SEM-EDS). The results obtained from the experimental work carried out in this research focused on the study of crude blends for low-energy cement created from industrial waste. The effect of the addition of different industrial waste types, as a substitution for raw materials, in the production of low-energy cement with high dicalcium silicate content has been investigated. Thus, the dosage design has been performed using modified Bogue equations and quality indexes (LSF, AM, and SM). The calculations of both the modified Bogue equations and quality indexes necessitate knowledge of the weight percentages of CaO, SiO2, Al2O3, and Fe2O3, determined via XRF. In this theoretical design of the different blends, it has been established that a dicalcium silicate ratio of 60-65 wt % and an LSF of 78-83% as the limit are values common to all of them. The calculation basis for the crude blends has been based on calcined materials. Therefore, the chemical composition was established, following this premise. Thus, it was possible to develop cement clinker blends with compositions of 50 wt % and 100 wt % using industrial wastes. This research has shown that the clinkerization process is one of the main options for the valorization of waste and its consideration for inclusion as a raw material within the circularity of the cement industry's production process. Thus, waste is used as a raw material for the production of a more useful substance, taking into account the fundamental principles of the circular economy.

Enero, 2023 | DOI: 10.3390/ma16020802

Thermal arrest analysis of the reverse martensitic transformation in a Ni55Fe19Ga26 Heusler alloy obtained by melt-spinning

Vidal-Crespo, A; Manchon-Gordon, AF; Blazquez, JS; Ipus, JJ; Svec, P; Conde, CF
Journal of Thermal Analysis and Calorimetry, (2023)
Reactividad de Sólidos


Ni55Fe19Ga26 ribbons obtained by melt-spinning technique exhibit a martensitic transformation from L2(1) cubic austenite phase to 14 M martensite phase above room temperature. We have taken advantage of the existence of thermal hysteresis of the martensitic phase transition (similar to 11 K) to analyze the effect of isothermal treatments on the reverse martensitic transformation, which has been analyzed by means of interrupted heating using differential scanning calorimetry. The experimental findings clearly indicate a time-depending effect in the martensitic transformation at temperatures between the austenite start and finish temperatures. Moreover, it has been observed that two successive martensitic transformations take place after the isothermal arrest was performed.

Enero, 2023 | DOI: 10.1007/s10973-022-11889-1

A novel, green, cost-effective and fluidizable SiO2-decorated calcium-based adsorbent recovered from eggshell waste for the CO2 capture process

Imani, M; Tahmasebpoor, M; Sanchez-Jim, P; Valverde, J; Garcia, VM
Separation and Purification Technology, 305 (2023) 122523
Reactividad de Sólidos


The reduction, storage, and reuse of greenhouse gas carbon dioxide (CO2) is a crucial concern in modern society. Bio-waste adsorbents have recently aroused the investigator's attention as auspicious materials for CO2 capture. However, the adsorption capacity decaying and poor fluidizability during carbonation/calcination cycles of all natural adsorbents used in the calcium-looping process (CaL) are important challenges. The current study ex-plores the performance of a novel SiO2-decorated calcium-based adsorbent recovered from eggshell waste in terms of both CO2 capture capacity and fluidity. Two preparation methods of hydration and sol-gel were used to obtain Ca-based adsorbents with different pore configurations and volumes. Modification of the adsorbents was applied by dry physically mixing with different weight percentages of hydrophobic SiO2 nanoparticles (NPs), in order to maintain stability and fluidity. The adsorbent prepared by the sol-gel method exhibited a fluffier structure with smaller grain sizes and higher porosity than that of prepared by the hydration method, leading to a 6.9 % increase in conversion at the end of the 20th cycle. Also, with the optimal amount of SiO2 nanoparticles, i. e. 7.5 wt%, the amount of CaO conversion obtained by sol-gel derived adsorbent was 27.59 % higher than that by pristine eggshell at the end of the 20th carbonation/calcination cycles. The fluidizability tests showed that the highest bed expansion ratio (2.29) was achieved for sol-gel derived adsorbent in the presence of 7.5 wt% silica nanoparticles which was considerably higher than the amount of 1.8 and 1.6 belonged to sol-gel derived adsorbent and pristine eggshell without silica at the gas velocity of approximate to 6.5 cm/s, respectively. The high adsorption capacity and proper fluidity of this novel and green calcium-based adsorbent promise its wide application.

Enero, 2023 | DOI: 10.1016/j.seppur.2022.122523

Highly dispersed Rh single atoms over graphitic carbon nitride as a robust catalyst for the hydroformylation reaction

Jurado, L; Esvan, J; Luque-Alvarez, LA; Bobadilla, LF; Odriozola, JA; Posada-Perez, S; Poater, A; Comas-Vives, A; Axet, MR
Catalysis Science & Tecnology
Química de Superficies y Catálisis


Rhodium-catalysed hydroformylation, effective tool in bulk and fine-chemical synthesis, predominantly uses soluble metal complexes. For that reason, the metal leaching and the catalyst recycling are still the major drawbacks of this process. Single-atom catalysts have emerged as a powerful tool to combine the advantages of both homogeneous and heterogeneous catalysts. Since using an appropriate support material is key to create stable, finely dispersed, single-atom catalysts, here we show that Rh atoms anchored on graphitic carbon nitride are robust catalysts for the hydroformylation reaction of styrene.

Enero, 2023 | DOI: 10.1039/d2cy02094g

Low Temperature Magnetic Transition of BiFeO3 Ceramics Sintered by Electric Field-Assisted Methods: Flash and Spark Plasma Sintering

Manchon-Gordon, AF; Perejon, A; Gil-Gonzalez, E; Kowalczyk, M; Sanchez-Jimenez, PE; Perez-Maqueda, LA
Materials, 16 (2023) 189
Reactividad de Sólidos


Low temperature magnetic properties of BiFeO3 powders sintered by flash and spark plasma sintering were studied. An anomaly observed in the magnetic measurements at 250 K proves the clear existence of a phase transition. This transformation, which becomes less well-defined as the grain sizes are reduced to nanometer scale, was described with regard to a magneto-elastic coupling. Furthermore, the samples exhibited enhanced ferromagnetic properties as compared with those of a pellet prepared by the conventional solid-state technique, with both a higher coercivity field and remnant magnetization, reaching a maximum value of 1.17 kOe and 8.5 10(-3) emu/g, respectively, for the specimen sintered by flash sintering, which possesses the smallest grains. The specimens also show more significant exchange bias, from 22 to 177 Oe for the specimen prepared by the solid-state method and flash sintering technique, respectively. The observed increase in this parameter is explained in terms of a stronger exchange interaction between ferromagnetic and antiferromagnetic grains in the case of the pellet sintered by flash sintering.

Enero, 2023 | DOI: 10.3390/ma16010189

Determination of the Primary Excitation Spectra in XPS and AES

Pauly, N; Yubero, F; Tougaard, S
Nanomaterials, 13 (2023) 339
Nanotecnología en Superficies y Plasma


This paper reviews a procedure that allows for extracting primary photoelectron or Auger electron emissions from homogeneous isotropic samples. It is based on a quantitative dielectric description of the energy losses of swift electrons travelling nearby surfaces in presence of stationary positive charges. The theory behind the modeling of the electron energy losses, implemented in a freely available QUEELS-XPS software package, takes into account intrinsic and extrinsic effects affecting the electron transport. The procedure allows for interpretation of shake-up and multiplet structures on a quantitative basis. We outline the basic theory behind it and illustrate its capabilities with several case examples. Thus, we report on the angular dependence of the intrinsic and extrinsic Al 2s photoelectron emission from aluminum, the shake-up structure of the Ag 3d, Cu 2p, and Ce 3d photoelectron emission from silver, CuO and CeO2, respectively, and the quantification of the two-hole final states contributing to the L3M45M45 Auger electron emission of copper. These examples illustrate the procedure, that can be applied to any homogeneous isotropic material.

Enero, 2023 | DOI: 10.3390/nano13020339


Is the RWGS a viable route for CO2 conversion to added value products? A techno-economic study to understand the optimal RWGS conditions

Portillo, E; Gandara-Loe, J; Reina, TR; Pastor-Perez, L
Science of the Total Environment, 857 (2023) 159394
Química de Superficies y Catálisis


Understanding the viability of the RWGS from a thermodynamic and techno-economic angle opens new horizons within CO2 conversion technologies. Unfortunately, profitability studies of this technology are scarce in literature and mainly focused on overall conversion and selectivity trends with tangential remarks on energy demands and pro-cess costs. To address this research gap, herein we present a comprehensive techno-economic study of the RWGS reac-tion when coupling with Fischer-Tropsch synthesis is envisaged to produced fuels and chemicals using CO2 as building block. We showcase a remarkable impact of operating conditions in the final syngas product and both CAPEX and OPEX. From a capital investment perspective, optimal situations involve RWGS unit running at low temperatures and high pressures as evidenced by our results. However, from the running cost angle, operating at 4 bar is the most favorable alternative within the studied scenarios. Our findings showcase that, no matter the selected temperature the RWGS unit should be preferentially run at intermediate pressures. Ultimately, our work maps out multiple operat-ing scenarios in terms of energy demand and process cost serving as guideline to set optimal reaction conditions to un-lock the potential of the RWGS for chemical CO2 recycling.

Enero, 2023 | DOI: 10.1016/j.scitotenv.2022.159394