On the Reactivity of the Cu/ZrO₂ System for the Hydrogenation of CO₂ to Methanol: A Density Functional Theory Study

Abstract

Zirconia-modified copper catalysts are being actively discussed to be beneficial in CO2/H2 conversion to methanol. The nature of the promotional effect of ZrO2 is still an intense matter of debate. Here, we report a density functional theory study investigating the CO2 hydrogenation reaction using a tetragonal ZrO2(101)-supported copper nanowire model of the copper–zirconia interface. We calculated adsorption energies of reactants and intermediates relevant for CO2 hydrogenation at different copper and zirconia adsorption sites. We suggest that in general adsorption at the Cu/ZrO2 interface and at zirconia facets is far too strong and that these sites will therefore be largely inactive for the hydrogenation of CO2 to methanol. We observe that adsorption at zirconia-supported copper sites further from the support is increased compared to that on unsupported Cu(111) and Cu(211) surfaces. We thus speculate that CO2 hydrogenation on these types of systems has the highest activity in close proximity to but not directly at the Cu/ZrO2 interface.