Electrochemical CO2 reduction integrated with membrane/adsorption-based CO2 capture in gas-diffusion electrodes and electrolytes

Electrochemical CO2 reduction integrated with membrane/adsorption-based CO2 capture in gas-diffusion electrodes and electrolytes

Electrochemical CO2 reduction reaction (CO2RR) has attracted much attention in the last decade, owing to its unique advantages such as operation at ambient conditions, coupling with renewable electricity, and producing a wide range of products and commodities. The majority of CO2RR studies are focused on pure CO2 as feed, while in real CO2 waste streams, such as flue gas or biogas, CO2 concentration does not exceed 40%. Therefore, the economic feasibility of CO2RR and its carbon footprint are greatly limited by the CO2 purification steps before electrolysis ($70–100 per ton of CO2 for CO2/N2 separation). In recent years, studies have exhibited the importance of this matter by integrating CO2 capture and electroreduction in a single unit. Mostly, CO2 capture solutions as electrolytes have been under attention, and promising results have been achieved to significantly improve the overall economy of CO2RR. The focus on CO2 capture-electroreduction integration can go beyond the solution/electrolyte-based CO2 capture (e.g., amine solutions and ionic liquids) and other processes such as solid adsorption and membrane-based processes, as more efficient options, can be potentially integrated with CO2 electroreduction in the gas-diffusion electrode design. This article aims to review the recent efforts in integrating capture and electroreduction of CO2 and provides new perspectives in material selection and electrode design for membrane- and adsorption-based CO2 capture-reduction integration, in addition to the analysis of the economic feasibility of this integration.