Influence of Ag Metal Dispersion on the Catalyzed Reduction of CO2 into Chemical Fuels over Ag-ZrO2 Catalysts.

Abstract

Metal/metal oxide catalysts reveal unique CO2 adsorption and hydrogenation properties in CO2 electroreduction for the synthesis of chemical fuels. The dispersion of active components on the surface of metal oxide has unique quantum effects, significantly affecting the catalytic activity and selectivity. Catalyst models with 25, 50, and 75% Ag covering on ZrO2, denoted as Ag4/(ZrO2)9, Ag8/(ZrO2)9, and Ag12/(ZrO2)9, respectively, were developed and coupled with a detailed investigation of the electronic properties and electroreduction processes from CO2 into different chemical fuels using density functional theory calculations. The dispersion of Ag can obviously tune the hybridization between the active site of the catalyst and the O atom of the intermediate species CH3O* derived from the reduction of CO2, which can be expected as the key intermediate to lead the reduction path to differentiation of generation of CH4 and CH3OH. The weak hybridization between CH3O* and Ag4/(ZrO2)9 and Ag12/(ZrO2)9 favors the further reduction of CH3O* into CH3OH. In stark contrast, the strong hybridization between CH3O* and Ag8/(ZrO2)9 promotes the dissociation of the C–O bond of CH3O*, thus leading to the generation of CH4. Results provide a fundamental understanding of the CO2 reduction mechanism on the metal/metal oxide surface, favoring novel catalyst rational design and chemical fuel production.