Thermo-Electrochemically Induced Dynamic Sn⁺/Sn Interface for Direct Bicarbonate Reduction to Formate

In traditional electrochemical CO2 reduction (ECR), pressurized pure CO2 gas is typically employed as the feedstock, which consumes large amounts of energy to capture and separate. Herein, we present a method for the direct bicarbonate reduction to formate on a cost-effective Sn foil electrode by integrating the thermochemical and electrochemical methods. Through the simultaneous thermal and electrochemical reactions on the Sn surface, a continuous Sn delta+/Sn redox loop was formed. This dynamic Sn delta+/Sn interface significantly boosts the direct reduction of bicarbonate to formate, resulting in an optimal partial current density of 121 mA cm(-2) for formate with an 83% Faradaic efficiency obtained in 3 mol L-1 KHCO3 at 100 degrees C. A detailed study revealed that the formate was produced from the bicarbonate directly rather than from the CO2 generated from the dissociation of bicarbonate at elevated temperatures. Compared to the traditional ECR, which involves the complicated processes of CO2 separation, compression, and recirculation, this research presents a straightforward and efficient way for direct bicarbonate reduction, holding promise for practical applications.