Density functional theory study of NOx adsorption on alkaline earth metal oxide and transition metal surfaces

Abstract

Since the emissions of nitrogen oxides (NOx) from automobiles cause air pollution, NOx storage-reduction (NSR) catalyst has been used to convert the NOx into harmless components such as N-2 through the reduction of NOx. In this study, to provide fundamental understanding of key elementary steps of NSR, we established an extensive database for the adsorption properties of NO and NO2 on a wide range of metal and metal oxide surfaces. Our results show that the amount of charge transfer between NOx and surface is closely related to the molecular adsorption strength of NOx, and it changes the molecular stability of NOx on the surfaces by enlarging the inner bond length of N-O. Understanding the adsorption energy of the molecules or atoms that would participate in the reaction can be important to predict the ability of NOx storage and conversion in NSR. This study provides a useful insight for designing metals or metal oxides for NSR catalyst.