Suppression of carbon deposition and sulfur poisoning without sacrificing electrochemical performance is crucial for operating solid oxide fuel cells (SOFCs), especially at intermediate temperatures (IT). In this work, nickel-doped A-site deficient perovskite oxides (PrBa)0.95Fe1.9-xNixMo0.1O6-δ (PBFMNix, x = 0, 0.1, 0.2, 0.3, 0.4) were synthesized and investigated as potential anodes for IT-SOFCs. With increased amounts of Ni2+, the ratios of Fe2+/Fe3+ and Mo5+/Mo6+ in as-prepared PBFMNix continuously decreased under a charge-compensating mechanism, which simultaneously depressed the formation of the impurity phase (BaMoO4). Interestingly, the substitution of Ni2+ benefits the reduction of Fe3+ to Fe2+ and Mo6+ to Mo5+, and small portions of Fe and Ni elements are exsolved from the parent oxides, forming FeNi3 alloy nano-particles that greatly accelerate the chemical adsorption and surface reaction kinetics of H2, and thus improve the electrochemical performances of oxide-based anodes. Transformation of the electrical conduction from p-type to n-type after reduction was also observed. A very small polarization resistance of 0.028 Ω cm2 at 750 °C was achieved for the cell with the PBFMNi0.3 anode. Importantly, fueled with syngas with 50 ppm H2S, the maximum power density of a button cell based on the PBFMNi0.3 anode and an Sm0.2Ce0.8O1.9 (SDC) electrolyte-supporting configuration can reach 498 mW cm-2 at 750 °C, and long-term stability over 100 hours can be demonstrated with negligible performance decay. All these results indicate that PBFMNi0.3 is a promising high-performance anode material with good coking resistance and sulfur tolerance in intermediate temperatures.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)