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

Abstract

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.