Metal‐Organic Framework Derived Bi‐O‐Sn/C Nanostructure: Tailoring the Adsorption Site of Dominant Intermediate for Highly Efficient CO₂ Electroreduction to Formate

Abstract

Electrochemical CO2 reduction into high‐value‐added formic acid/formate is an attractive strategy to mitigate global warming and achieve energy sustainability. However, the adsorption energy of most catalysts for the key intermediate *OCHO is usually weak, and how to rationally optimize the adsorption of *OCHO is challenging. Here, an effective Bi‐Sn bimetallic electrocatalyst (Bi1‐O‐Sn1@C) where a Bi‐O‐Sn bridge‐type nanostructure is constructed with O as an electron bridge is reported. The electronic structure of Sn is precisely tuned by electron transfer from Bi to Sn through O bridge, resulting in the optimal adsorption energy of intermediate *OCHO on the surface of Sn and the enhanced activity for formate production. Thus, the Bi1‐O‐Sn1@C exhibits an excellent Faradaic efficiency (FE) of 97.7% at −1.1 V (vs RHE) for CO2 reduction to formate (HCOO−) and a high current density of 310 mA cm−2 at −1.5 V, which is one of the best results catalyzed by Bi‐ and Sn‐based catalysts reported previously. Impressively, the FE exceeds 93% at a wide potential range from −0.9 to −1.4 V. In‐situ ATR–FTIR, in‐situ Raman, and DFT calculations confirm the unique role of the bridge‐type structure of Bi‐O‐Sn in highly efficient electrocatalytic reduction of CO2 into formate.