Sr-Doped PrCrO₃ with Intelligent SrCrOx Cocatalyst for the Fuel Electrode of Reversible Solid Oxide Cells

Reversible solid oxide cells (RSOCs) are energy-conversion devices that can convert electricity into chemical energy and vice versa. The working environment of the fuel electrode would vary significantly between the two modes and the design of an efficient and durable fuel electrode is urgent and demanding. In this work, Pr1–xSrxCrO3 (x = 0.2, 0.3) perovskites were explored, aiming to find proper fuel electrodes for a RSOC. A minor amount of SrCrO4 was produced in Pr0.8Sr0.2CrO3 (PS20C) and Pr0.7Sr0.3CrO3 (PS30C) under oxygenation and can be reduced to SrCrO3−δ by reduction in 5% H2. The polarization resistance (Rp) value of PS30C was significantly lower than PS20C (0.15 Ω cm2 versus 2.11 Ω cm2) at 800 °C and the higher performance of the PS30C fuel electrode could be related partially to the production of more metallic SrCrO3−δ. A high performance was obtained in either fuel cell mode or electrolysis mode using a PS30C fuel electrode with the intelligent SrCrOx and the additional Ni infiltration does not enhance the performance. Ru infiltration into the PS30C further enhances the cell performance, imparting a peak power of 832 mW cm–2 as fuel cell and a current density of 1.19 A cm–2 at 1.3 V for steam electrolysis at 800 °C. The reversible switching at 0.6 V for H2 oxidation and 1.3 V for steam electrolysis was tested for 12 cycles, and insignificant performance degradation was found for the PS30C cell with Ru infiltration. This work advances the development of PrCrO3 perovskite with metallic oxide SrCrOx cocatalyst for high-performance RSOC fuel electrodes.