Controllable Synthesis of Few-Layer Bismuth Subcarbonate by Electrochemical Exfoliation for Enhanced CO2 Reduction Performance.

Two-dimensional (2D) engineering of materials has been recently explored to enhance the performance of electrocatalysts by reducing their dimensionality and introducing more catalytically active ones. In this work, controllable synthesis of few-layer bismuth subcarbonate nanosheets has been achieved via an electrochemical exfoliation method. These nanosheets catalyse CO2 reduction to formate with high faradaic efficiency and high current density at a low overpotential owing to the 2D structure and co-existence of bismuth subcarbonate and bismuth metal under catalytic turnover conditions. Two underlying fast electron transfer processes revealed by Fourier-transformed alternating current voltammetry (FTacV) are attributed to CO2 reduction at bismuth subcarbonate and bismuth metal. FTacV results also suggest that protonation of CO2.- is the rate determining step for bismuth catalysed CO2 reduction.