Complete catalytic cycle of NO decomposition on a silicon-doped nitrogen-coordinated graphene: Mechanistic insight from a DFT study

Abstract

The abatement of NO with efficient technology and low operation cost is still a challenging mission worldwide. By application of DFT calculations, we systematically investigate the complete catalytic cycles of NO conversion on the single Si atom doped in four pyridinic N at the divacancy site of graphene. The effects of O2, CO and water in exhausted gas are considered. The SiN4G catalyst is highly active to NO while CO is essential for recovering the catalyst surface after NO decomposition. The catalyst shows resistance to water which is a positive effect for NO abatement technology. Furthermore, the synergy between the Si atom and coordinating nitrogen atoms greatly enhances the catalytic activity towards NO reactions. This metal-free catalyst exhibits higher catalytic activity for both NO reduction and oxidation in mild conditions compared with those catalysts doped only with Si or coordinated only with N on graphene. With presence of O2, NO oxidation only requires 0.2 eV activation energy, while NO reduction also occurs easily in the absence of O2. Both oxidation and reduction reactions are exothermic processes. Therefore, incorporating Si and N on graphene could provide a low-cost and highly efficient method of fabricating catalyst for large-scale reaction of NO abatement.