Mutual Conversion of CO-CO 2 on a Perovskite Fuel Electrode with Endogenous Alloy Nanoparticles for Reversible Solid Oxide Cells.

Reversible solid oxide cells (RSOCs) can efficiently render the mutual conversion between electricity and chemicals, for example, electrolyzing CO 2 to CO under a solid oxide electrolysis cell (SOEC) mode and oxidizing CO to CO 2 under a solid oxide fuel cell (SOFC) mode. Nevertheless, the development of RSOCs is still hindered, owing to the lack of catalytically active and carbon-tolerant fuel electrodes. For improving mutual CO-CO 2 conversion kinetics in RSOCs, here, we demonstrate a high-performing and durable fuel electrode consisting of redox-stable Sr 2 (Fe, Mo) 2 O 6-δ perovskite oxide and epitaxially endogenous NiFe alloy nanoparticles. The electrochemical impedance spectrum (EIS) and distribution of relaxation time (DRT) analyses reveal that surface/interface oxygen exchange kinetics and the CO/CO 2 activation process are both greatly accelerated. The assembled single cell produces a maximum power density (MPD) of 443 mW cm -2 at 800 °C under the SOFC mode, with the corresponding CO oxidation rate of 5.524 mL min -1 cm -2 . On the other hand, a current density of -0.877 A cm -2 is achieved at 1.46 V under the SOEC mode, equivalent to a CO 2 reduction rate of 6.108 mL min cm -2 . Furthermore, reliable reversible conversion of CO-CO 2 is proven with no performance degradation in 20 cycles under SOEC (1.3 V) and SOFC (0.6 V) modes. Therefore, our work provides an alternative way for designing highly active and durable fuel electrodes for RSOC applications.