Porous Bi Nanosheets Derived from β-Bi₂O₃ for Efficient Electrocatalytic CO₂ Reduction to Formate

The electrochemical CO₂ reduction reaction (ECO₂RR) is a promising strategy for converting CO₂ into high-value chemical products. However, the synthesis of effective and stable electrocatalysts capable of transforming CO₂ into a specified product remains a huge challenge. Herein, we report a template-regulated strategy for the preparation of a Bi₂O₃-derived nanosheet catalyst with abundant porosity to achieve the expectantly efficient CO₂-to-formate conversion. The resultant porous bismuth nanosheet (p-Bi) not only exhibited marked Faradaic efficiency of formate (FE_formate), beyond 91% in a broad potential range from -0.75 to -1.1 V in the H-type cell, but also demonstrated an appreciable FE_formate of 94% at a high current density of 262 mA cm^-2 in the commercially important gas diffusion cell. State-of-the-art X-ray absorption near edge structure spectroscopy (XANES) and theoretical calculation unraveled the distinct formate production performance of the p-Bi catalyst, which was cocontributed by its smaller size, plentiful porous structure, and stronger Bi-O bond, thus accelerating the absorption of CO₂ and promoting the subsequent formation of intermediates. This work provides an avenue to fabricate bismuth-based catalysts with high planar and porous morphologies for a broad portfolio of applications.