Gaseous CO<sub>2</sub> Electrolysis: Progress, Challenges, and Prospects
Junhyeong Kim, Wenwu Guo, Hedam Kim, Seonghyun Choe, Soo Young Kim, Sang Hyun Ahn
Abstract
Human activities increase CO2 concentration in the atmosphere, causing serious global climate change. CO2 electrolysis is a promising technology for removing CO2 and producing valuable C2+ products, and its commercialization mainly relies on the development of advanced systems with a fast conversion rate, high conversion efficiency, and high product selectivity at minimized overpotentials. In conventional systems, a CO2-dissolved aqueous solution is used as the reactant, which limits the maximum current density to ∼35 mA/cm2 for products owing to low CO2 solubility, thereby resulting in sluggish diffusion of CO2 from the bulk electrolyte to the catalyst surface. This problem can be solved by emerging gaseous CO2 electrolysis systems with gas diffusion electrodes that are capable of accelerating the conversion rate with enhanced CO2 diffusion. However, challenges exist regarding encountering performance degradation owing to the local environment change in the system during operation. This Perspective highlights the recent progress in gaseous CO2 electrolysis systems categorized based on the cell configuration and the major challenges that must be overcome before commercialization of this technology.