Molybdenum(Mo)‐doped ceria (CMO) nanoparticles were synthesized by the combustion method with three different Mo compositions: 5 wt.%, 7 wt.%, and 10 wt.%. The catalytic activity of CMO for wet gasification of carbon was studied in a fluidized bed reactor, while the mechanical and electrical properties of this material were characterized using dense sintered CMO pellets. The Young's modulus was found to increase with the Mo content; the higher value measured was 289.4 GPa for CMO with 10 wt.% Mo. Measurements of Vickers microhardness demonstrated that an increase in the Mo content produces a decrease in the microhardness of the material, suggesting that Mo confers semi‐metallic characteristics to CMO. The higher fracture toughness value, determined by the Niihara equation, was 4.39 MPa m0.5 for CMO with 10 wt.% Mo. In addition, an increase in the molybdenum content produced an increase in the electrical conductivity under air and H2 atmospheres. The maximum electrical conductivities under air and H2 were found for CMO with 10 wt.% Mo at 800 °C: 1.87 × 10−3 S cm−1 and 9.37 × 10−1 S cm−1, correspondingly. Finally, CMO with 10 wt.% Mo exhibited good catalytic activity for carbon gasification, which renders it a promising material for a combined fluidized bed‐SOFC system.
Yttrium-doped copper tungstate photoelectrodes are prepared by depositing an yttrium-doped CuWO4 film (Y-CuWO4) on conductive glass substrates by dip coating. The morphology and chemical composition confirm the fabrication of yttrium-doped CuWO4 films. The optical bandgap of the photoelectrodes is studied by UV-Vis diffuse reflectance and a bandgap of 2.30 eV is obtained for the pure CuWO4 photoelectrode. The yttrium-doped photoelectrodes show a small shift of the bandgap to higher values, which according to DFT calculations can be ascribed to a higher density of electronic states in the first conduction band from incorporating yttrium into the structure. The photoelectrochemical characterisation shows that adding yttrium produces an enhanced charge separation efficiency in the bulk which can be attributed to a higher donor density in the structure, and a 92.5% higher photocurrent density is obtained for the 5%Y-CuWO4 photoelectrode when compared to the pure CuWO4 photoelectrode for the oxygen evolution reaction at 1.3 V vs RHE. This work shows that doping CuWO4 with yttrium is an effective approach to improve the poor charge separation presented by pure CuWO4 photoelectrodes.
Artículo de publicación ISIImpurities and additives play a key role in copper electrodeposition, in particular in upstream processes such as electrowinning or electrorefining. One common impurity is iron, mostly present as iron species Fe(II) in highly concentrated sulfuric acid solutions and in a cathodic environment. Herein, the kinetics of copper electrodeposition from such solutions have been investigated using a copper rotating disk electrode and alternating current voltammetry (ACV). For a concentration of proton of 1.84 M and a concentration of Fe(II) ions of 0.054 M, the deposition kinetics are slow enough to separately observe the two electron transfer steps involved in copper reduction: an observation unique to ACV. The results suggest that Fe(II) ions affect the electrodeposition kinetic by slowing down reaction kinetics, in particular slowing the second electron transfer reaction.MISTI-Chile progra
Future progress in hybrid and battery vehicles heavily relies on the optimization of involved battery components and lubricants. Attention must specifically be given to the material composition and surface coatings of the electrodes as well as the electrolyte used to maximize energy output, while also ensuring safety. Additionally, prioritizing the effective utilization of specific lubricants for electric motors and various tribological contacts, such as wheel bearings and the steering system, is the prospective goal of lubrication research. The energy output of the most promising battery, the Li-ion battery (LIB), must result in driving ranges, which can compete with the 600 km driving range of combustion engine (ICE) vehicles. Consequently, ongoing research activities in cell chemistry, electrode surface engineering, electrolyte engineering, and engine lubrication offer the greatest opportunity in achieving these goals.
High temperature direct carbon fuel cells (DCFCs) offer potentially high efficiencies for conversion of the chemical energy of solid carbonaceous fuel(s) into electrical energy. DCFCs with molten metal anodes consume carbonaceous fuels by oxygen dissolved within the melt, which functions as an anode in an otherwise conventional solid oxide fuel cell (SOFC). Such reactors can also be used in electrolytic mode for reducing steam to hydrogen at the cathode, which enables the specific electrical energy consumption for H 2 production to be decreased compared with conventional steam electrolysis. 2-D models have been developed to predict the behavior of a micro-tubular hollow fiber SOFC (ca. 1 mm ID) with a molten metal (Sn) anode, using assumed values for the anode exchange current density. Results are reported for the temperature dependence of open circuit potentials for the reactor: Sn | SnO 2 | YSZ | Air measured using a pellet cell and compared with thermodynamic predictions.
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