Advancements and prospects of perovskite-based fuel electrodes in solid oxide cells for CO electrolysis to CO.

Carbon dioxide (CO) electrolysis to carbon monoxide (CO) is a very promising strategy for economically converting CO, with high-temperature solid oxide electrolysis cells (SOECs) being regarded as the most suitable technology due to their high electrode reaction kinetics and nearly 100% faradaic efficiency, while their practical application is highly dependent on the performance of their fuel electrode (cathode), which significantly determines the cell activity, selectivity, and durability. In this review, we provide a timely overview of the recent progress in the understanding and development of fuel electrodes, predominantly based on perovskite oxides, for CO electrochemical reduction to CO (CORR) in SOECs. Initially, the current understanding of the reaction mechanisms over the perovskite electrocatalyst for CO synthesis from CO electrolysis in SOECs is provided. Subsequently, the recent experimental advances in fuel electrodes are summarized, with importance placed on perovskite oxides and their modification, including bulk doping with multiple elements to introduce high entropy effects, various methods for realizing surface nanoparticles or even single atom catalyst modification, and nanocompositing. Additionally, the recent progress in numerical modeling-assisted fast screening of perovskite electrocatalysts for high-temperature CORR is summarized, and the advanced characterization techniques for an in-depth understanding of the related fundamentals for the CORR over perovskite oxides are also reviewed. The recent pro-industrial application trials of the CORR in SOECs are also briefly discussed. Finally, the future prospects and challenges of SOEC cathodes for the CORR are suggested.