Scalable Chemical Interface Confinement Reduction BiOBr to Bismuth Porous Nanosheets for Electroreduction of Carbon Dioxide to Liquid Fuel

Abstract Electrochemical reduction of carbon dioxide (CO 2 ) toward chemical and fuel production is a compelling component of the new energy system. Two‐dimensional bismuth with a particular surface has been identified as a highly efficient electrocatalyst for converting CO 2 to formate. However, the development of a controllable synthetic strategy for possible large‐scale production of such Bi materials remains highly challenging. Herein, a scalable chemical interface confinement reduction method is proposed for topotactic transformation of BiOBr (001) nanosheets to metallic Bi (001) porous nanosheets (PNS). As expected, the Bi (001) PNS exhibits excellent electrochemical performance on CO 2 reduction to formate, with Faradaic efficiency of 95.2% and formate partial current density of 72 mA cm −2 . Density functional theory calculations suggest that Bi PNS selectively exposes (001) surfaces with small‐angle grain boundaries can significantly lower the free energy barrier for the formation of *OCHO, which are responsible for the high activity and selectivity toward CO 2 ‐to‐formate conversion.