Elucidating the structure-dependent selectivity of CuZn towards methane and ethanol in CO2 electroreduction using tailored Cu/ZnO precatalysts

Understanding the catalyst compositional and structural features that control selectivity is of uttermost importance to target desired products in chemical reactions. In this joint experimental-computational work, we leverage tailored Cu/ZnO precatalysts as a material platform to identify the intrinsic features of methane-producing and ethanol-producing CuZn catalysts in the electrochemical CO2 reduction reaction (CO2RR). Specifically, we find that Cu@ZnO nanocrystals, where a central Cu domain is decorated with ZnO domains, and ZnO@Cu nanocrystals, where a central ZnO domain is decorated with Cu domains, evolve into Cu@CuZn core@shell catalysts that are selective for methane (similar to 52%) and ethanol (similar to 39%), respectively. Operando X-ray absorption spectroscopy and various microscopy methods evidence that a higher degree of surface alloying along with a higher concentration of metallic Zn improve the ethanol selectivity. Density functional theory explains that the combination of electronic and tandem effects accounts for such selectivity. These findings mark a step ahead towards understanding structure-property relationships in bimetallic catalysts for the CO2RR and their rational tuning to increase selectivity towards target products, especially alcohols.

Automated summary

Understanding the compositional and structural features of catalysts controlling selectivity is crucial in chemical reactions. This study leveraged tailored Cu/ZnO precatalysts to identify intrinsic features of CuZn catalysts for CO2 reduction, revealing Cu@CuZn core@shell structures selective for methane and ethanol. Surface alloying and metallic Zn concentration were found to improve ethanol selectivity, with density functional theory explaining the selectivity based on electronic and tandem effects. These findings contribute to the rational tuning of bimetallic catalysts for CO2 reduction towards increased selectivity, especially for alcohols.