Synergistic effect of oxygen vacancies and edging/corner-connected MnO6 structural motifs in multi-dimensional manganese oxides to enhance OVOCs catalytic oxidation

Abstract

The structure-activity relationships for vinyl acetate catalytic oxidation are challenging to explore at the atomic scale due to the ambiguity of the structural defect types and sites of manganese oxides. Our work elaborates, at the atomic level, through in-situ experimental and theoretical methods, the synergistic effects of two types of structural defect sites of VO-e (edge-sharing oxygen) and VO-c (corner-sharing oxygen) and MnO6 structural motifs of manganese oxides. Multi-dimensional manganese oxides, namely those with corner-connected MnO6 structural motifs and VO-c structural oxygen defect sites, significantly improved the activation of vinyl acetate. Enhancement of enol structure formation, acetate and formate intermediate species, and tautomerism between enol structure and acetaldehyde were detected when oxygen vacancies of manganese oxides were present in combination with corner/edge-connected MnO6. Moreover, the activation of chemical bonds and deep catalytic oxidation of vinyl acetate depend on the presence of a redox couple, surface oxygen species, and weakened MnO bonds. It provides a valuable notion for investigating and designing catalytic systems and reaction processes for the purpose of emission reduction and the management of environmental contaminants.