Exploring reaction mechanism of CO oxidation over SrCoO3 catalyst: A DFT study

Abstract

Perovskite-type oxides are considered to be the promising catalysts for CO oxidation. However, little attention has been paid to the SrCoO3 perovskite, and the atomic-level reaction mechanism that dictates the reactivity of CO oxidation over SrCoO3 catalyst remains elusive. Herein, the oxidation mechanism of CO on the SrCoO3 surface was studied by density functional theory (DFT) calculations. The results indicate that CO and O2 adsorption on the SrCoO3(100) surface are controlled by the chemisorption. The Co-terminated surface is more active for CO oxidation than the Sr-terminated surface. The adsorption energy (−0.94 eV) of CO is higher than that (−0.69 eV) of O2. The reaction pathway of CO oxidation over SrCoO3 catalyst was investigated by analyzing three possible reaction mechanisms, including the Eley-Rideal mechanism, Langmuir-Hinshelwood mechanism, and Mars-van Krevelen mechanism. The interaction between chemisorbed CO and surface lattice oxygen plays an important role in CO oxidation on the SrCoO3(100) surface. CO oxidation occurs mainly through the Mars-van Krevelen mechanism due to the lower energy barrier. CO* + Olattice → CO2* + Ovacancy is the rate-determining step as it has the highest activation energy barrier (0.61 eV) during CO oxidation reaction. These mechanistic insights can help to better understand the microcosmic reaction process to boost the CO oxidation activity of SrCoO3 catalyst.