Unravelling the electrocatalytic activity of bismuth nanosheets towards carbon dioxide reduction: Edge plane versus basal plane

Abstract Electrochemical reduction of CO2 (ECO2RR) to formate is one of effective approaches to achieve carbon recycling processes. Despite Bi nanosheets (NSs) have been proven to be highly selective in ECO2RR to formate, the understanding of the true active sites is needed to further dig out the potential of catalytic activity of Bi NSs. In this work, we developed a rational synthesis approach to manipulate the basal-/edge-plane ratio of Bi NSs via topotactic reduction of (004)-oriented Bi5O7I NSs and (102)-oriented BiOI NSs to reveal the contribution of basal and edge planes on the performance of ECO2RR. In comparison with edge-oriented Bi NSs, basal-oriented Bi NSs show higher catalytic activity. DFT calculations have proven that the competition of the kinetically favored HER would be inhibited on basal planes of Bi NSs, indicating the increasement of the proportion of basal planes on Bi NSs or Bi based 2D catalysts improves ECO2RR conversion efficiency.