Mo‐doped CeO₂ Synthesized by the Combustion Method for Carbon‐Air Solid Oxide Fuel Cell (CA‐SOFC) Applications

Abstract

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.

Mo,Cu-doped CeO2 as Anode Material of Solid Oxide Fuel Cells (SOFCs) using Syngas as Fuel

“…The plots for the total electrical conductivity (σ) of pure ceria, CMO10 [7] and CMCuO under air atmosphere as a function of temperature are shown in Fig. 2(a).…”

“…The electrical conductivity measurements were performed under ultra-pure air atmosphere (100 mL min -1 flow rate) and the results obtained were compared with the data reported in the literature for pure CeO 2 (ceria) and Mo-doped CeO 2 with 10 wt.% molybdenum content (CMO10) [7]. The electrical connections were made with 4 spots of silver paste (Fuel Cells Materials) and silver wires (99.99% metal basis and 0.5 mm of diameter), connecting the silver wires with the surface of the sintered disc.…”

“…1(c), indicates that CMCuO crystallizes as a Fm-3m fluorite-type structure, likewise its CMO10 parent [7]. The displacement of the peaks in the XRD pattern of CMCuO with respect to the peaks in the XRD pattern of CMO10, which is confirmed by the change in the lattice parameter calculated for CMCuO (5.424 Å) with respect to the lattice parameter of CMO10 (5.421 Å [7]), can be related to the inclusion of Cu into the crystalline structure of ceria. This would promote the formation of oxygen vacancies and add electrons in the Ce-sites in accordance with the reaction in Eq.…”

“…Recently, Mo-doped CeO 2 has been reported as a stable ceria-based anode material with higher catalytic activity for carbon gasification and electrical conductivity than pure CeO 2 (a value of ca. 1.87•10 -3 S cm -1 at 800 o C was measured under air atmosphere for Modoped CeO 2 with 10 wt.% Mo), although this latter needs to be at least one order of magnitude larger for SOFC applications [7].…”

Active Tuning of Optical Constants in the Visible–UV: Praseodymium‐Doped Ceria—a Model Mixed Ionic–Electronic Conductor

“…In this study, we demonstrate both chemical and electrical means for achieving high‐level and reversible optical tuning in the visible–UV spectrum in mixed ionic–electronic conducting oxides, utilizing praseodymium (Pr)‐substituted cerium (Ce) oxide, Pr 0.1 Ce 0.9 O 2– δ (PCO), as a model system. Ce oxide is known to be flexible in hosting a variety of dopants from lanthanide [ 24 ] and transition metal [ 25 ] groups; thus, the tuning mechanisms of optical properties presented in this work are expected to exhibit different optical responses for the different dopant types that can even be combined in the same host lattice, allowing for a richer tunable color design gamut.…”