Selectivity switch in transformation of CO2 from ethanol to methanol on Cu embedded in the defect carbon

The copper-based catalysts have been generally regarded as high-performance catalysts for CO_2 hydrogenation toward methanol,while the production of ethanol via C–C coupling on the copper-based catalysts is still challenging.Herein,we report a new catalyst where Cu nanoparticles are embedded in the carbon support with abundant defect sites,achieving a high selectivity for ethanol in the CO_2 hydrogenation.The experiments coupled with the theoretical studies show a clear map where carbon defects serve as anchor sites that can stabilize interfacial copper species,and interfacial Cu sites with low coordination numbers can adsorb two C_1 species and later convert them to a C_2 species via a hydrogenation-induced coupling reaction.Further adjacent Cu atoms of interfacial Cu sites can facilitate OH reduction reactions via the Cu–Cu bridge adsorption to assist the formation of ethanol.Especially,those specific active sites easily disappear in the reducing conditions and during the reaction,the major product can transform from ethanol to methanol.