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.