Promoting Selective CO<sub>2</sub> Electroreduction to Formic Acid in Acidic Medium with Low Potassium Concentrations under High CO<sub>2</sub> Pressure
Florian Lhostis, Ngoc‐Huan Tran, Gwenaëlle Rousse, Sandrine Zanna, Nicolas Menguy, Marc Fontecave
Abstract
Abstract Electrocatalytic CO 2 reduction reaction (CO 2 RR) offers a sustainable pathway for the production of chemicals and fuels. Acidic electrolysis has been shown to be a promising strategy in order to avoid CO 2 loss via the formation (bi)carbonate during reaction. Previous studies have been carried out in ambient CO 2 pressure systems and have stressed the importance of adding high concentration of alkali cation (K + ) in the catholyte to inhibit the hydrogen evolution reaction (HER) and achieve higher selectivity of CO 2 RR. Herein, CO 2 reduction to HCOOH was performed in strong acid (pH 1) using a dendritic bismuth catalyst in a home‐designed high‐pressure electrochemical cell. At a CO 2 pressure of 30 bar, we could achieve a high Faradaic efficiency of 100 % at 100 mA cm −2 at a KCl concentration of 3.0 M. With this first system that combines high pressure of CO 2 and highly acidic catholyte, we show that pressurization offers an appropriate strategy to limit both HER and K + dependence. Indeed we obtained a Faradaic efficiency of 34 % in the absence of K + cations and 75–80 % in the presence of 1.0 M KCl under an applied current density of 100 mA cm −2 .