Tuning the local coordination environment of silver(I) coordination networks with counterions for enhanced electrocatalytic CO2 reduction

Very recently, the local coordination environment of active sites has been found to strongly influence their performance in electrocatalytic CO2 reduction by tuning the intrinsic kinetics of CO2 activation and intermediate stabilization. It is imperative to elucidate the mechanism for such an influence towards the rational design of efficient catalysts; however, the complex interactions between the multiple factors involved in the system make it challenging to establish a clear structure-performance relationship. In this work, we chose ion-intercalated silver(I)-based coordination networks (AgCNs) with a well-defined structure as a model platform, which enables us to understand the regulation mechanism of counterions as the counterions are the only tuning factor involved in such a system. We prepared two isostructural AgCNs with different intercalation ions or counterions of BF4− and ClO4− (named as AgCNs-BF4 and AgCNs-ClO4) and found that the former has a more competitive CO2 electroreduction performance than the latter. AgCNs-BF4 achieves the highest Faradaic efficiency for CO2 to CO of 87.1 BF_4^ - is more favorable for stabilizing the COOH* intermediate by weakening hydrogen bonds, which accounts for the superior activity of AgCNs-BF4.