Vanadium-Doped Strontium Molybdate with Exsolved Ni Nanoparticles as Anode Material for Solid Oxide Fuel Cells

Vanadium-doped strontium molybdate (SVM) has been investigated as a potential anode material for solid oxide fuel cells due to its high electronic conductivity of about 1000 S cm^-1 at 800 °C in reducing atmospheres. In this work, NiO is introduced to SVM with the B-site excess design to induce in situ growth of Ni nanoparticles in the anodic operational conditions. The Ni particles are exsolved from the parent oxide phase as clearly demonstrated with various techniques including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The exsolved Ni nanoparticles significantly boost the electrocatalytic activity toward fuel oxidation reaction, improving the peak power density by 160% from 0.21 to 0.56 W cm^-2 at 800 °C when using H₂ as the fuel, meanwhile reducing the total interfacial polarization resistance by 56% from 0.81 to 0.36 Ω cm². The Ni-exsolved SVM anode also shows excellent catalytic activity toward H₂S-containing and hydrocarbon fuels, providing peak power densities of 0.43, 0.36, and 0.22 W cm^-2 at 800 °C for H₂-50 ppm H₂S, syngas, and ethanol, respectively. In addition, the cell with the Ni-exsolved SVM anode presents a stable power output, indicating that the Ni-SVM is a potential SOFC anode electrocatalyst for various fuels.