Grain boundaries assisting the generation of abundant Cu+ for highly selective electroreduction of CO2 to ethanol

Abstract

It is highly desired yet challenging to strategically steer the CO₂ electroreduction reaction (CO₂ER) toward ethanol (EtOH) with high activity and selectivity. Although the grain boundary (GB) has been identified as an effective active site for C2 product formation, there is still no consensus on the mechanism governing its regulation. Moreover, the specific Cu species that plays a crucial catalytic role remains a source of debate. Herein, we report a type of Cu₇Se₄/CuSe nanosheets with rich GBs, which are conducive to the generation of abundant Cu⁺ species. Crucially, a clear correlation between Cu⁺ content and EtOH selectivity is obtained. The unique local charge distribution and electronic structure of Cu on GBs make it a real active site to promote EtOH production. This work elucidates the significant role of the chemical state of Cu in CO₂ER toward EtOH, shedding light on the mechanistic insights of GBs serving as active sites for this process.