Promotion mechanism of pyridine N-doped carbocatalyst for SO2 oxidation

Abstract

Pyridine N (PyN) doped carbon materials have long been recognized as promising catalysts for SO₂ oxidation under mild conditions, but our understanding of what is happening at the atomic level is still limited. Herein, the local structure and promotion mechanism of PyN in carbon materials for the catalytic oxidation of SO₂ were investigated on graphene model catalysts by using density functional theory. A type of defect involving three PyN atoms around a single C atom vacancy was found to be active for both the dissociation of O₂ and the further oxidation of SO₂. It is worth mentioning that both PyN and the adjacent C atoms are primary active sites. Additionally, a switch effect of pyridine N-oxide was identified, which can suppress or enhance the oxidation capacity of surface oxygen species for SO₂ oxidation. These results provide a mechanistic explanation for the low temperature catalytic oxidation of SO₂ by PyN-doped carbon materials and offer insight for the design of new carbon-based catalysts.