Concurrent promotion of phase transition and bimetallic nanocatalyst exsolution in perovskite oxides driven by Pd doping to achieve highly active bifunctional fuel electrodes for reversible solid oxide electrochemical cells

The reducibility of B-site elements in perovskite (ABO3) structures is one of the paramount factors that promote the in-situ exsolution of metallic nanocatalysts, and the phase transition of the support to a more stable structure under solid oxide cell (SOC) fuel electrode operating conditions. Herein, we develop a highly catalytically active and durable perovskite-based fuel electrode material—La0.6Sr0.4Co0.15Fe0.8Pd0.05O3- δ (LSCFP)—for reversible SOCs. The LSCFP material under the fuel electrode condition is fully transformed into a stable Ruddlesden-Popper phase decorated by bimetallic Co-Fe nanocatalysts. The SOC with LSCFP fuel electrode yielded outstanding performances in both fuel cell (2.00 W cm−2) and electrolysis cell (2.23 A/cm2 at 1.3 V) modes at 850 °C, with remarkable reversible-cyclic stability. These results clearly demonstrate that the novel LSCFP capable of concurrent phase transition and bimetallic exsolution in the reducing condition is a highly prospective candidate as a bifunctional fuel electrode for reversible SOCs.