Density Functional Theory Study Of The Formaldehyde Catalytic Oxidation Mechanism On A Au-Doped Ceo2(111) Surface

Formaldehyde is a harmful and toxic substance. Au-CeO2 catalysts show the excellent formaldehyde catalytic oxidation activity even under ambient temperatures. Here, we present the DFT+U calculations to investigate HCHO oxidation mechanisms and the effects of Au doping and multiple oxygen vacancies. The reaction process of HCHO oxidation mainly consists of the following steps: HCHO adsorption, C-H bond cleavages, CO2 desorption, O-2 adsorption, and H2O formation and desorption. The doped Au reduces the energy barriers in C-H bond cleavages on the AuCe1-xO2(111) surface compared with the CeO2(111) surface. Au also leads to the activation of the surface oxygen species and then promotes HCHO adsorption and decreases the formation energies of oxygen vacancies. For HCHO adsorption and oxidation reaction on defective surfaces, catalysts with more oxygen vacancies possess higher adsorption energy and lower activation energy. These results provide deep insights into the effects of Au and multiple oxygen vacancies on HCHO oxidation reactions on the Au-doped CeO2(111) surface and reveal the essential reason for the high activity of Au-CeO2 catalysts.