The bovine carbonic anhydrase promoted dehydration of bicarbonate to CO2 for the electrochemical production of syngas

Abstract

The electrochemical reduction of CO2 into value-added products is a promising strategy for carbon footprint mitigation. Current research efforts are focused on combining this strategy with CO2 capture in bicarbonate-based solvents to build an efficient CO2 capture and utilization system. The primary challenge to address in this system is the development of a cost-effective CO2 regeneration method that will enable the CO2 gas feed to be continuously recovered from the bicarbonate capture medium for utilization. In this work, we studied systems for CO2 utilization, integrated with the bicarbonate dehydration activity of bovine carbonic anhydrase (BCA) to recover CO2 for the electrochemical production of syngas. Specifically, we investigated the generation of CO2 from bicarbonate catalyzed by BCA in the free form or immobilized on the electrode surface and the consequent Au-catalyzed electrochemical reduction of CO2 to CO. We showed that BCA functions efficiently in 2 M KHCO3 at pH 9 to promote the release of CO2 from an external compartment to the Au electrocatalyst in the CO2 reduction reaction electrolyzer, thereby achieving a significant faradaic efficiency of 27% for the CO product. This work demonstrates a sustainable and environmentally friendly approach for the electrochemical utilization of captured CO2.