Cation Deficiency Tuning of LaCoO₃ Perovskite as Bifunctional Oxygen Electrocatalyst

Oxygen electrocatalysis, including both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), dominates the performance of various electrochemical energy conversion and storage systems. However, the practical applications of these devices are limited as a result of the sluggish kinetics of OER and ORR as well as the high cost and instability of the state-of-the-art noble metal catalyst used in these systems. In this study, cation deficiency is introduced to the A-site of perovskite LaCoO₃ synthesized via polymer-assisted approach to enhance the electrocatalytic activity of both OER and ORR, leading to the boosted bifunctionality of the resultant electrocatalysts, which might be attributed to oxygen vacancy introduction in perovskites. The bifunctionality of the A-site deficiency perovskite (ΔE=0.948 V) is comparable or even better than the pristine LaCoO₃ (ΔE=1.063 V) as well as the reported state-of-the-art electrocatalysts, including both perovskites and noble metal electrocatalysts. The stability test also indicates their good stability under alkaline solutions, suggesting that the as-prepared materials can be good candidates as bifunctional electrocatalysts in oxygen-based electrochemical devices, such as fuel cells and metal-air batteries. This work introduces the A-site cation deficiency strategy to improve the bifunctional electrocatalytic performance of perovskites, and highlights the facile polymer-assisted approach for perovskites synthesis.