The method of introducing oxygen vacancy into La_0.8Sr_0.2FeO₃-based catalyst: enhancing the ORR and OER performance

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been widely used in energy conversion devices; therefore, the demand for corresponding catalysts is increasing each year. Pt and IrO₂ are considered to be the most advanced ORR and OER catalysts; however, these expensive precious metal catalysts hinder their extensive application in practical applications. Herein, a series of La_0.8Sr_0.2FeO₃-based perovskite catalysts (La_0.8Sr_0.2FeO₃-PEI, La_0.8Sr_0.2FeO₃-Fe₂O₃, La_0.8Sr_0.2FeO₃) have been created by sol–gel method to achieve highly efficient catalytic performance for ORR and OER and these perovskite oxides stand out with raw material availability to substitute noble metal as bi-functional composite catalysts. The superior ORR performance (the onset potential is 1.061 V and the half-wave potential is 0.672 V), significant enhancement of OER performance (the onset potential is 1.553 V and current density is 5.53 mA cm⁻² at 1.8 V) and the electron transfer number (3.69) of La_0.8Sr_0.2FeO₃-PEI are significantly higher than those of two others, which benefited from the introducing of carbon in the preparation of perovskite, increasing the oxygen vacancy concentration on the surface of the catalyst, adsorbing more highly reactive oxygen species O₂²⁻/O⁻, and enhancing the ORR and OER performance of the catalyst. This article suggests that carbon introducing is a promising strategy to improve the electrocatalytic activity for ORR and OER.