Atomically dispersed Ag on δ-MnO2via cation vacancy trapping for toluene catalytic oxidation

Abstract

The regulation of metal–support interaction (MSI) and the improvement of noble metal utilization are the frontiers of volatile organic compound (VOC) catalytic oxidation. Here, we report a H₂O₂-assisted synthesis process for trapping Ag⁺ onto the engineered Mn vacancies of δ-MnO₂ for the catalytic oxidation of toluene. Due to the strong MSI between Ag and δ-MnO₂, the monoatomic Ag⁺ anchored on cation vacancies forms longer and weakened Ag–O bonds compared with Ag₂O, which can extra promote the formation of oxygen vacancies and the activation of adjacent lattice oxygen in Ag–O–Mn units compared with regular nanoparticle counterparts. It is beneficial to the steps of methyl dehydrogenation, demethylation, and benzene ring cleavage. The catalyst yields excellent toluene oxidation activity, enhanced turnover frequency in terms of Ag, and good stability. We propose in this study a facile design strategy for fabricating stably atomically dispersed metal sites, as well as clarify the structure–activity relationships during toluene catalytic oxidation, especially the important effect of single-atom Ag on the adjacent local structure.