Engineering oxygen vacancies in perovskite oxides by in-situ electrochemical activation for highly efficient nitrate reduction

Perovskite oxides have emerged as a new category of catalysts for NO3RR, yet their low intrinsic catalytic activity results in unsatisfactory performance. Oxygen vacancy engineering has recently been found to be effective for improving the NO3RR performance of perovskite oxides. Herein, a novel and efficient strategy of electrochemical activation for in-situ oxygen vacancies (OVs) creation in perovskite oxide La0.9FeO3-δ was reported. The results showed that the NO3--N removal rate increased 2.6-fold on activated La0.9FeO3-δ in comparison to pristine La0.9FeO3-δ. The enhanced NO3RR performance was attributed to the presence of more OVs, which served to increase the adsorption energy of NO3- while also promoting atomic H* formation for NO3--N hydrogenation. Furthermore, a continuous experiment lasting 240 hours found the activated La0.9FeO3-δ exhibited extremely high stability. Additionally, we demonstrated that the electrochemical activation method was applicable to other typical perovskite oxides, such as LaCoO3, indicating its generalizability. This study provides a simple and scalable approach for the preparation of a high-performance perovskite oxide-type electrocatalysts for NO3RR.