Exploiting thiolate/disulfide redox couples toward large-scale electrochemical carbon dioxide capture and release†

Abstract

Reducing global carbon dioxide (CO₂) emissions is a critical issue that requires sustainable, energy-efficient and scalable solutions. Electrochemical carbon dioxide capture and release with redox active molecules has drawn an intense amount of interest, owing to its mild operation conditions, low energy consumption and high flexibility compared with traditional CO₂ capture technologies. Here, we demonstrate a series of thiolate/disulfide redox couples, with high practical solubility and weak protonation ability, which are able to reversibly capture and release CO₂. The mechanism of CO₂ capture and release using such redox couples is elucidated via combining density functional theory (DFT) calculations, cyclic voltammetry and Fourier transform infrared (FTIR) spectroscopy measurements. Furthermore, we show that the redox performance of such materials can be significantly improved by functional group tuning and electrolyte engineering. Among them, the 4-fluorophenyl thiolate/4-fluorophenyl disulfide redox couple shows an initial CO₂ capacity utilization efficiency and average release/capture efficiency of ∼100% and ∼90%, respectively, under simulated flue gas (20% CO₂) in a flow system. Besides, it exhibits good cycling stability against moisture. This work opens new opportunities to future works in developing thiolate/disulfide redox couples for large-scale electrochemical carbon dioxide capture and release applications.