Si-embedded graphene: an efficient and metal-free catalyst for CO oxidation by N2O or O2

Abstract

As is well known, searching for an efficient catalyst for CO oxidation is of great importance in the removal of poisonous CO gas. From the results of density functional theory calculations, we have reported the catalytic oxidation of CO by O2 or N2O on Si-embedded graphene. Both Langmuir–Hinshelwood and Eley–Rideal mechanisms of CO oxidation on Si-embedded graphene were comparably studied. The results indicate that CO oxidation by O2 on Si-embedded can occur via a two-step mechanism: (1) CO + O2 → OOCO → CO2 + O, followed by (2) CO + O → CO2. The energy barriers for the two steps are 0.48 and 0.57 eV, respectively. For N2O + CO → N2 + CO2, N2O firstly interacts with Si-embedded graphene, releasing N2 and leaving the O-atom to be attacked by the subsequent CO to yield CO2 to proceed with the catalytic cycle. The present results provide a useful guidance to fabricate metal - free graphene-based catalysts for CO oxidation with low cost and high activity.