Electrochemical conversion of low-concentration carbon dioxide to multicarbon products: advances, challenges, and perspectives.

Abstract

Electrocatalytic CO2 reduction reaction (CO2RR) offers a promising route to valorize CO2 streams and to store renewable electricity in the form of chemicals and fuels. High-purity CO2 gas has been widely used as the feedstock for most of the CO2RR studies, while real-world CO2 sources typically have a low concentration with various contaminants, requiring extra cost for CO2 capture and purification steps. The direct utilization of low-concentration and impurity-containing CO2 for the CO2RR offers a practical approach to substantially address this problem. Furthermore, compared with C1 products, multicarbon (C2+) ones are more desirable due to their higher energy density and more significant market needs. Considering the lack of a timely review on the state-of-the-art progress of electrochemical conversion of low-concentration CO2 to C2+ products, developing an appropriate and prompt summary of such a rapidly growing field with a comprehensive understanding is necessary. In this review, we explore the recent progress in direct electrolysis of low-concentration CO2 to C2+ products from several aspects, including design strategies for the diluted CO2RR to C2+ products, treatment methods for the CO2RR to C2+ products in a gas-impurity-containing CO2 atmosphere, direct electrolysis of CO2 capture solutions to C2+ products, and bioelectrocatalytic conversion of CO2 to C2+ products. Significantly, the technoeconomic analysis of low-concentration CO2 electroreduction is presented, including cost components, output metrics, and a survey of recent case studies on low-concentration CO2-to-C2+ conversion. Finally, we propose an outlook on future challenges and some opportunities for this promising research field.

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