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

Abstract

Reversible solid oxide cells (RSOCs) are energyconversion 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, Pr 1−x Sr x CrO 3 (x = 0.2, 0.3) perovskites were explored, aiming to find proper fuel electrodes for a RSOC. A minor amount of SrCrO 4 was produced in Pr 0.8 Sr 0.2 CrO 3 (PS20C) and Pr 0.7 Sr 0.3 CrO 3 (PS30C) under oxygenation and can be reduced to SrCrO 3−δ by reduction in 5% H 2 . The polarization resistance (R p ) value of PS30C was significantly lower than PS20C (0.15 Ω cm 2 versus 2.11 Ω cm 2 ) at 800 °C and the higher performance of the PS30C fuel electrode could be related partially to the production of more metallic SrCrO 3−δ . A high performance was obtained in either fuel cell mode or electrolysis mode using a PS30C fuel electrode with the intelligent SrCrO x 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 H 2 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 PrCrO 3 perovskite with metallic oxide SrCrO x cocatalyst for high-performance RSOC fuel electrodes.