Promoting electrocatalytic activity of single-phase semiconductor Y₃Fe₅O₁₂ (YIG) dual-functional cathode/electrolyte for ceramic fuel cells

To construct hybrid functions of electrolyte and cathode materials has improved fuel cell power output and structural stability at low operational temperatures as a novel approach in ceramics fuel cells (CFC) research. We found that semiconductor material Y3Fe5O12 possesses dual-functions of electrolyte and cathode, which has been systematically studied on the ion transport, oxygen kinetics, redox reaction, and electrochemical performance. The sintering temperature strongly affects the YIG, resulting in weak metal oxygen (M-O) bonds, more active sites and enrich oxygen vacancies, which provide both an active surfaces towards oxygen reduction and high oxide ion conductivity. The hybrid functional YIG exhibits good peak power output of 423 mW/cm(2) (as an electrolyte) and 531 mW/cm(2) (as an cathode) at 540 C-degrees, respectively. Moreover, YIG displays outstanding oxygen reduction reaction (ORR) and catalytic activity during the electrochemical measurements. This work may offer a novel strategy for developing hybrid functions for ceramic fuel cells to enable low operational temperatures.