Theoretical study of oxidative removal on the CeO2(110) surface for formaldehyde: in-depth investigation of oxygen vacancy and chemisorbed oxygen
Abstract
Thermal catalytic oxidation (TCO) technology is one of the effective methods to remove formaldehyde. CeO2, known for its oxygen storage capacity (OSC), is a promising rare earth material for the thermal catalytic oxidation of formaldehyde. The oxidation mechanism of formaldehyde on the CeO2(110) surface was investigated by density functional theory (DFT). Herein, formaldehyde and oxygen could not be stably adsorbed on a stoichiometric CeO2(110) surface, which was verified by charge-density difference and PDOS analysis. The defective CeO2(110) surface strengthened the adsorption of formaldehyde and oxygen by filling oxygen vacancies and evolved the free oxygen into chemisorbed oxygen. Formaldehyde was difficult to dehydrogenate on stoichiometric or defective CeO2(110) surfaces without oxygen. The water-forming capacity of chemisorbed oxygen promoted the dehydrooxidation of formaldehyde. It not only greatly reduced the energy barrier for the rate-determining step in the formaldehyde oxidation process but also helped formaldehyde to complete a complete oxidation cycle pathway.