Shifting CO2 hydrogenation from producing CO to CH3OH by engineering defect structures of Cu/ZrO2 and Cu/ZnO catalysts

The catalytic performance of supported Cu catalysts in CO2 hydrogenation is structurally dependent; hence, regulating the metal-support interactions, often driven by the redox feature of the metal oxide supports, can potentially improve catalytic performance. In this work, we demonstrate an enhanced strong metal-support interaction (SMSI) and electronic metal-support interaction (EMSI) in Cu/ZrO2 and Cu/ZnO after introducing oxygen vacancies into the catalyst supports, evidenced by more Cu encapsulation by oxide overlayers and electron transfer from the defective supports to Cu after introducing the oxygen vacancies. As a result, the defective Cu/ZrO2 and Cu/ZnO catalysts showed markedly improved MeOH production rather than CO production in the CO2 hydrogenation reaction. The in situ FTIR studies showed that the CO2 molecules preferentially adsorbed and activated into bicarbonate rather than carbonate, followed by a rapid conversion into formate on the defective catalyst. These findings highlight the special effects of defective supports in CO2 activation and conversion and catalyst design and synthesis.