Defect engineering in SnO2 catalysts for the organic oxidation reaction

Defect engineering in metal oxides is an effective approach for improving advanced oxidation processes. Herein, we report that regulating the defect types present on SnO enables deconvolution of their distinct effects on organic oxidation. Nitrogen annealing created E′ center and non-bridging oxygen hole center (NBOHC) defects, while optimum hydrogenation introduced oxygen vacancies, significantly enhancing catalytic oxidation performance. Based on spectroscopic analysis, extended hydrogenation times passivated NBOHCs and formed new types of defects, such as electrons trapped in oxygen vacancies, which are less catalytically active in comparison with NBOHCs. DFT indicated that oxygen vacancies lower the energy barrier for oxygen activation as well as activation of the C-H bonds in formic acid, corroborating the experimental results of enhanced catalytic activity in samples with optimized defect concentrations. The current work advances understanding of the roles different defects play in enhancing organic oxidation in the ongoing search for efficient materials for oxidation reactions.