Highly Unsaturated Oxygen Promotes Formaldehyde Catalytic Oxidation on the Defective Co3o4 (111) Surface: A Dft Study

Abstract

The active oxygen, which was generated through surface oxygen vacancy, showed high activities in HCHO catalytic oxidation by Co3O4 but why the active oxygen was so highly active remained unclear. In this study, density functional theory calculations were performed to unravel the role of active oxygen in HCHO catalytic oxidation on the Co3O4 (111) surface. The reaction paths of HCHO catalytic oxidation on perfect and defective Co3O4 (111) surfaces via three possible reaction mechanisms (MvK, E-R and L-H) were investigated. The results showed that, on the perfect Co3O4 (111) surface, the HCHO catalytic oxidation only followed the MvK mechanism. On the defective Co3O4 (111) surface, owing to the highly active oxygen, the L-H mechanism showed great advantage because of the extremely low energy barrier of 0.1 eV for the first C-H bond cleavage. Further electronic structure calculations revealed that the high activity of active oxygen was mainly attributed to its high unsaturation degree, which induced a strong attraction of active oxygen to the H of HCHO and promoted C-H bond cleavage.

Keywords: Co3O4, HCHO, DFT, Catalytic oxidation, oxygen vacancy