In-situ formation of hydroxylated Ag active sites over Ag/MnO2 modified by alkali metals for stable decomposition of ozone under humid conditions

Abstract

Ag/MnOx catalysts have great prospects for practical application in ozone decomposition due to their excellent activity and water resistance; yet, improving the stability of Ag/MnOx catalysts for ozone decomposition remains challenging. Here, the addition of alkali metals significantly improved the stability of 2%Ag/MnO2 catalyst for ozone decomposition under humid conditions. Alkali metals donate electrons to Ag nanoparticles through oxygen bridges, forcing Ag active sites to become hydroxylated by promoting the dissociation of H2O molecules, and finally forming new stable hydroxylated Ag active sites (Ag-O(OH)x-K). The O22- species on the new active sites of the 2%K-2%Ag/MnO2 catalyst can easily desorb; therefore, the hydroxylated active sites can remain stable. These factors are key to the stable ozone decomposition activity of 2%K-2%Ag/MnO2 catalyst in humid gas. This study represents a critical step towards the design and synthesis of high-stability catalysts for ozone decomposition.