Surface Mn-O3* complex-mediated nonradical electron transfer for boosting catalytic ozonation of organic pollutants

Abstract

As initial and important reactive species, surface O complexes are rarely investigated in catalytic ozonation, which might be one cause of dispute in mechanistic understanding. Herein, In-situ DRIFTS and premixing-standing experiments confirmed the generation of long-lived Mn-O* complexes upon O adsorption on surface Lewis acid sites of α-MnO. In α-MnO/O system, the oxidation rate of various pollutants showed a good linear correlation with their redox potentials, as well as the energy gap between the pollutants and Mn-O* complexes. Joint catalytic mechanism experiments and density functional theory calculations revealed that the oxidation of pollutants was boosted mainly because there was fast nonradical intermolecular electron transfer from the HOMO of pollutants to the LUMO of Mn-O* complexes. This study illustrates the significance of surface Mn-O* complex in catalytic ozonation and discloses an efficient nonradical catalytic ozonation process that is resistant to pH fluctuation and matrix interference.