Geopolymer Based Electrodes as New Class of Material for Electrochemical CO2 Reduction

Abstract

To achieve a successful transition to a sustainable carbon and energy management, it is essential to both reduce CO2 emissions and develop new technologies that utilize CO2 as a starting substrate. In this study, we demonstrate for the first-time the functionalization of geopolymer binder (GP) with Sn for electrochemical CO2 reduction (eCO2RR) to formate. By substituting cement with Sn-GP, we have merged CO2 utilisation and emission reduction. Using a simple mixing procedure, we were able to obtain a pourable mortar containing 5 vol. % Sn-powder. After hardening, the Sn-GP electrodes were characterized for their mechanical and CO2 electrolysis performance. In 10 h electrolyses, formate concentrations were as high as 22.7±0.9 mmol L−1 with a corresponding current efficiency of 14.0±0.5 % at a current density of 20 mA cm−2. Our study demonstrates the successful design of GP-electrodes as a new class of hybrid materials that connect eCO2RR and construction materials.