New Sr2FeMo0.5X0.5O6 (X1/4Ni, Co, Mn, Zn) cathodes for proton-conducting SOFCs

Transition metal elements were employed to customize the standard Sr2Fe1.5Mo0.5O6 (SFM) material, with the goal of improving the performance of the SFM cathode in protonconducting solid oxide fuel cells (H-SOFCs). Sr2FeMo0.5X0.5O6 (X = Ni, Co, Mn, Zn) materials were prepared, but it was discovered that only the dopants Ni and Co can form a pure phase, whereas the dopants Mn and Zn produced an obvious secondary phase. When comparing oxygen vacancies and oxygen diffusion kinetics, utilizing the Co-dopant exhibited clear advantages. The Co-doped SFM had a higher oxygen vacancy content and faster oxygen diffusion kinetics than both the standard and Ni-doped SFM cathodes. The energy barrier for the oxygen reduction reaction (ORR) at the Co-doped SFM cathode was 0.76 eV, which was much lower than that for the SFM and Ni-doped SFM, which were 5.52 and 2.28 eV, respectively. As a result, the Co-doped SFM's cathode reaction was greatly accelerated, resulting in a high fuel cell performance of 1306 mW cm-2 at 700 degrees C. This finding suggests that using the appropriate dopant can alleviate the low-performance problem of the traditional SFM cathode, resulting in a promising cathode option for H-SOFCs. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.