Oxygen vacancy engineering for tuning the catalytic activity of LaCoO3 perovskite

Abstract

Herein, we attempted to engineer oxygen vacancies on the surface of LaCoO3 perovskite through simple post-treatments (acid or reductive thermal treatments). Acid treatment induces oxygen vacancies through the selective etching of the La cations, whereas thermal treatment in a reducing atmosphere generates oxygen vacancies by directly removing lattice oxygen. The characterization results confirm that the number of surface oxygen vacancies, which are crucial in various catalytic oxidation reactions, considerably increases in the LaCoO3 catalysts treated with acid or reducing gas. Acid treatment enriches the oxygen vacancies while maintaining the structure of the LaCoO3 catalysts, which can not be achieved through reductive thermal treatment. Therefore, the acid treatment is considered a promising technique for oxygen vacancy engineering of perovskite catalysts for tuning their catalytic activities. Furthermore, the catalytic activities of the posttreated LaCoO3 catalysts for CO oxidation were evaluated and are noted to be considerably better than those of the pristine LaCoO3 catalyst due to their abundant oxygen vacancies. Consequently, we conclude that the oxygen vacancies of perovskite catalysts can be effectively engineered via two simple methods and play a significant role in CO oxidation.