Active copper structures in ZnO–Cu interfacial catalysis:CO_(2) hydrogenation to methanol and reverse water–gas shift reactions

Cu–ZnO-based catalysts are widely used to catalyze the CO_(2) hydrogenation to methanol and reverse water–gas shift(RWGS)reactions.Herein,via a combined experimental and theoretical calculation study of various Cu nanocrystals(NCs) with welldefined Cu facets and corresponding Zn O/Cu NC inverse catalysts,we demonstrate the Cu{110} facets as the most active facet for ZnO–Cu interfacial catalysis in the CO_(2) hydrogenation to methanol with an apparent activation energy as low as 25.3±3 kJ mol^(-1) and the Cu{100} facets as the most active facet for both ZnO–Cu interfacial catalysis and Cu catalysis in the RWGS reaction.Although the ZnO–Cu interface is more active in catalyzing the RWGS reaction than the Cu surface,the RWGS reaction occurs mainly on the bare Cu surface of ZnO/Cu inverse catalysts under the CO_(2) hydrogenation to methanol instead of that at the ZnO–Cu interface.This fundamental understanding will greatly help to fabricate efficient Cu–ZnO-based catalysts for the CO_(2) hydrogenation to methanol.