Cu Facet-Dependent Elementary Surface Reaction Kinetics of CO2 Hydrogenation to Methanol Catalyzed by ZrO2/Cu Inverse Catalysts

Abstract

ZrO₂-Cu-based catalysts are active in catalyzing the hydrogenation of CO₂ to methanol. Herein, we report Cu facet effects on the catalytic performance of ZrO₂/Cu inverse catalysts in CO₂ hydrogenation to methanol using various Cu nanocrystals with well-defined Cu morphologies and facets. The ZrO₂-Cu interface is the active site, in which the ZrO₂-Cu{100} and ZrO₂-Cu{110} interfaces exhibit similar apparent activation energies of ∼42.6 kJ/mol, smaller than that of the ZrO₂-Cu{111} interface (∼64.5 kJ/mol). Temporal in situ diffuse reflectance infrared Fourier transform spectroscopy characterization results identify the bridge formate hydrogenation as the rate-determining elementary surface reaction under typical reaction temperatures, whose activation energy is similar at the ZrO₂-Cu{100} (∼36.3 kJ/mol) and ZrO₂-Cu{110} (∼40.5 kJ/mol) interfaces and larger at the ZrO₂-Cu{111} interface (∼54.5 kJ/mol). This fundamental understanding suggests Cu facet engineering as a promising strategy to improve the catalytic performance of ZrO₂/Cu inverse catalysts for CO₂ hydrogenation to methanol.