Atomic dispersion of Ag on Mn2O3 for soot catalytic oxidation: Dispersion mechanism and catalytic intermediate identification

Abstract

The investigation of active site evolution and reaction intermediates during the catalytic oxidation process has paramount importance for the development of highly efficient catalysts for soot oxidation. Nevertheless, soot oxidation involves complex gas‒solid‒solid reaction pathways, and challenges persist in precisely investigating the active sites and intermediates. Herein, single-atom Ag₁O₅ catalysts with uniform active sites were constructed from Ag nanoparticles assisted by the interplay between the surface defects of Mn₂O₃ and temperature-induced diffusion. Based on the use of Ag₁/Mn₂O₃ as a model catalyst and in situ environmental electron microscopy results, the soot particles show diffusion behavior toward the Ag₁/Mn₂O₃ catalyst, and the Ag single-atom active sites significantly decrease the required reaction temperature for soot oxidation. Consequently, the oxidation reaction occurs at the active sites of the individual Ag atoms, leading to the formation of AgC intermediates. This research provides critical insights for the design and fabrication of highly efficient and stable catalysts for soot oxidation.