Integrated CO₂ capture and electrochemical upgradation: the underpinning mechanism and techno-chemical analysis

Coupling post-combustion CO₂ capture with electrochemical utilization (CCU) is a quantum leap in renewable energy science since it eliminates the cost and energy involved in the transport and storage of CO₂. However, the major challenges involved in industrial scale implementation are selecting an appropriate solvent/electrolyte for CO₂ capture, modeling an appropriate infrastructure by coupling an electrolyser with a CO₂ point source and a separator to isolate CO₂ reduction reaction (CO₂RR) products, and finally selection of an appropriate electrocatalyst. In this review, we highlight the major difficulties with detailed mechanistic interpretation in each step, to find out the underpinning mechanism involved in the integration of electrochemical CCU to achieve higher-value products. In the past decades, most of the studies dealt with individual parts of the integration process, i.e., either selecting a solvent for CO₂ capture, designing an electrocatalyst, or choosing an ideal electrolyte. In this context, it is important to note that solvents such as monoethanolamine, bicarbonate, and ionic liquids are often used as electrolytes in CO₂ capture media. Therefore, it is essential to fabricate a cost-effective electrolyser that should function as a reversible binder with CO₂ and an electron pool capable of recovering the solvent to electrolyte reversibly. For example, reversible ionic liquids, which are non-ionic in their normal forms, but produce ionic forms after CO₂ capture, can be further reverted back to their original non-ionic forms after CO₂ release with almost 100% efficiency through the chemical or thermal modulations. This review also sheds light on a focused techno-economic evolution for converting the electrochemically integrated CCU process from a pilot-scale project to industrial-scale implementation. In brief, this review article will summarize a state-of-the-art argumentation of challenges and outcomes over the different segments involved in electrochemically integrated CCU to stimulate urgent progress in the field.