In situ unraveling effect of dynamic chemical state on selective CO2 reduction upon zinc electrocatalyst

Unraveling the reaction mechanism behind CO2 reduction reaction (CO2RR) is a crucial step for advancing the development of efficient and selective electrocatalyst to yield valuable chemicals. To understand the mechanism of zinc electrocatalyst toward CO2RR, a series of thermally oxidized zinc foils is prepared to achieve a direct correlation between chemical state of electrocatalyst and product selectivity. The evidence provided by in situ Raman spectroscopy, X-ray absorption spectroscopy (XAS) and X-ray diffraction significantly demonstrat that the Zn(II) and Zn(0) species on surface is responsible for the production of carbon monoxide (CO) and formate, respectively. Specifiaclly, the destruction of dense oxide layer on the surface of zinc foil through thermal oxidation process results in a 4-fold improvement of faradaic efficiency (FE) of formate toward CO2RR. The results from in situ measurements reveal that the chemical state of zinc electrocatalysts could dominate the product profile for CO2RR, which provides a promising approach for tuning the product selectivity of zinc electrocatalyst.