Thermo-Electrochemically Induced Dynamic Sn<sup>δ+</sup>/Sn Interface for Direct Bicarbonate Reduction to Formate
Yuhou Pei, Wen Gu, Shuo Cheng, Shuhan Xiao, Chunling Wang, Yang Yang, Heng Zhong, Fangming Jin
Abstract
In traditional electrochemical CO 2 reduction (ECR), pressurized pure CO 2 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 δ+ /Sn redox loop was formed. This dynamic Sn δ+ /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 KHCO 3 at 100 °C. A detailed study revealed that the formate was produced from the bicarbonate directly rather than from the CO 2 generated from the dissociation of bicarbonate at elevated temperatures. Compared to the traditional ECR, which involves the complicated processes of CO 2 separation, compression, and recirculation, this research presents a straightforward and efficient way for direct bicarbonate reduction, holding promise for practical applications.