Thermo-electrocatalytic reduction of potassium bicarbonate to formate on an indium electrode

Abstract In this work, we developed a thermo-electrochemical bicarbonate reduction (TEBR) process for the production of formate on a simple indium foil electrode. The TEBR process relies on the synergistic effect of thermochemical and electrochemical processes, which ensures the continuous redox of metals on the electrode surface. In the thermochemical environment, indium can interact with water to form InO(OH), which facilitates the absorption and hydrogenation of bicarbonate to form formate. In the electrochemical environment, the reduction of indium oxide to indium supports the maintenance of a dynamic interface of In3+/In. This study revealed that, when an indium electrode is employed in the reaction system, the Faraday efficiency and partial current density of formate can reach 86.2% and 86.5 mA cm−2, respectively, at 100 °C with a KHCO3 concentration of 3.0 mol L−1. Therefore, an indium electrode can be effectively employed for the direct reduction of bicarbonate to produce formate. This study provides an insight into the synergistic effect of thermochemical and electrochemical processes, and suggests a potential application of indium in the production of formate via a TEBR process.