High-oxygen vacancy cerium catalysts with NiFe alloy heterostructures: A pathway for efficient and stable biomass ethanol fuel tubular solid oxide fuel cells

Hydrocarbon fuels have the advantages of being low-cost, easy to store and transport, and can be converted into biomass gas through oxidation and reforming processes, further increasing their potential applications. However, incomplete reforming and carbon deposition under practical conditions hinder the utilization of hydrocarbon fuels. In this work, Ni_0.1Fe_0.1Ce_0.8O_2−δ (NFCO) is employed as the anode reforming catalyst for tubular solid oxide fuel cells (T-SOFCs) with low-concentration ethanol-carbon dioxide fuel. With the in situ-formed NiFe alloy, the T-SOFC with NFCO achieves peak power densities of 538, 614, and 608 mW·cm⁻² in 5%, 10%, and 15% ethanol, respectively, which are higher than those of the cell without NFCO. More importantly, no significant degradation is observed during long-term operation. As confirmed by density functional theory (DFT) calculations, the introduction of a NiFe alloy on the basis of CeO₂ significantly improved the adsorption energy of H₂O, thereby increasing the adsorption capacity of water molecules and promoting the adsorption and conversion of ethanol fuel. The results indicate that the heterostructure between the NiFe alloy and high-oxygen-vacancy CeO₂ enhances the anode catalytic activity and inhibits the carbon deposition of T-SOFCs under low-concentration ethanol-carbon dioxide fuel, providing important insights for the development of high-performance, carbon-tolerant T-SOFCs under direct hydrocarbon fuel.