Dynamic Self‐Healing of the Reconstructed Phase in Perovskite Oxides for Efficient and Stable Electrocatalytic OER

Abstract

Neither electrocatalytic activity nor structural stability is inconsequential in water electrolysis. Unfortunately, they have to be compromised in practice, especially in the anodic redox chemistry of lattice oxygen. Herein, the discovery of a La_1- _xCe_xFeO₃ perovskite is presented which shows both good stability and high catalytic activity. Using advanced operando characterizations, it is identified that the self-healing evolution of the La_1- _xCe_xFeO₃ perovskite plays a key role during water oxidation in the lattice oxygen-mediated mechanism (LOM) pathway. Unlike irreversible reconstruction, the formation of reconstructed active-phase α-FeOOH is reversed by re-crystallization of surface La_1- _xCe_xFeO₃ upon return to noncatalytic conditions. The self-healing transformation of the α-FeOOH termination layer on the stable La_1- _xCe_xFeO₃ core imparts remarkable long-term stability as well as excellent electrocatalytic performance. As a result, a composition La_0.9Ce_0.1FeO₃@FeOOH is designed that exhibits ultralow overpotentials of 257 and 312 mV to achieve 10 and 100 mA cm^-2, respectively. The findings provide insight into self-healing behavior toward engineering perovskite oxides for efficient and stable oxygen electrocatalysis.