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.