Metal-organic Layers Derived Atomically Thin Bismuthene for Efficient Carbon Dioxide Electroreduction to Liquid Fuel.

: Electrochemical reduction of CO2 to valuable fuels is appealing for CO2 fixation and energy storage. However, the development of electrocatalysts with high activity and selectivity in a wide potential window is challenging. Herein, atomically thin bismuthene (Bi-ene) is pioneeringly obtained via an in situ electrochemical transformation process from ultrathin bismuth-based metal-organic layers. The few-layer Bi-ene, which possesses a great mass of exposed active sites with high intrinsic activity, simultaneously exhibit considerable high selectivity (~100%), large partial current density and pretty good stability in a record wide potential window exceeding 0.35 V toward formate production. Furthermore, it even can deliver extraordinary current densities exceed 300.0 mA cm-2 without compromising selectivity in a flow cell reactor. Furthermore, by virtue of in situ ATR-IR spectra and DFT analysis, a new HCO3- participated reaction mechanism for formate generation was firstly unveiled, which brings new fundamental understanding of CO2 reduction.