Strategies to Enhance CO2 Electrochemical Reduction from Reactive Carbon Solutions

Abstract

CO2 electrochemical reduction (CO2 ER) from (bi)carbonate feed presents an opportunity to efficiently couple this process to alkaline-based carbon capture systems. Likewise, while this method of reducing CO2 currently lags behind CO2 gas-fed electrolysers in certain performance metrics, it offers a significant improvement in CO2 utilization which makes the method worth exploring. This paper presents two simple modifications to a bicarbonate-fed CO2 ER system that enhance the selectivity towards CO. Specifically, a modified hydrophilic cathode with Ag catalyst loaded through electrodeposition and the addition of dodecyltrimethylammonium bromide (DTAB), a low-cost surfactant, to the catholyte enabled the system to achieve a FECO of 85% and 73% at 100 and 200 mA·cm−2, respectively. The modifications were tested in 4 h long experiments where DTAB helped maintain FECO stable even when the pH of the catholyte became more alkaline, and it improved the CO2 utilization compared to a system without DTAB.