Sr₂Fe_1.5Mo_0.4Ti_0.1O_6-δ perovskite anode for high-efficiency coal utilization in direct carbon solid oxide fuel cells

Efficient and direct utilization of coal-based fuels is the developmental direction of direct carbon solid oxide fuel cells (DCSOFCs), but their performance is hindered by poor catalytic activity and contaminant poisoning of anode materials. Herein, a Ti-doped double perovskite oxide Sr₂Fe_1.5Mo_0.4Ti_0.1O_6-δ (SFMT) was developed as the coal-based DCSOFC anode to improve its catalytic activity and resistance to sulfur poisoning. X-ray photoelectron spectroscopy confirms that SFMT shows abundant oxygen vacancy concentration under reducing atmosphere. The as-fabricated DCSOFC with the SFMT anode delivers a maximum power density of 506.5 mW cm⁻² at 800 °C when using bituminous coal as the fuel. Electrochemical impedance spectroscopy reveals that Ti doping can effectively promote electrochemical processes on the anode side. Both thermogravimetric analysis and CO temperature-programmed desorption demonstrate that the performance improvement of SFMT is ascribed to its promoted catalytic activity in coal gasification and its increased CO adsorption capacity. The operational period of this coal-based DCSOFC increases from 2 to 10 h after Ti doping, which can be explained by the enhanced structural stability of SFMT under a sulfur-containing environment. Our work may provide some new insight on the design of high-activity anode materials and the understanding of anode reaction mechanisms for coal-based DCSOFCs.