Anion effects govern efficiency of electrochemical amine-mediated CO2 capture/release

Abstract

Abstract Ambient electrochemical CO 2 capture powered by renewable energy offers a promising carbon removal route, exemplified by the emerging electrochemically mediated amine regeneration (EMAR) process demonstrated in lab-scale single cells and stacks. However, molecular-level insight into EMAR interfacial kinetics is still missing, particularly at the anode, where CO 2 release involves a mechanistically non-trivial re-complexation process at the electrode–electrolyte interface, coupling heterogeneous metal-ion release with bulk complexation. Here, we report the time-resolved characterization of the interfacial molecular processes of the EMAR CO 2 release process. Using in situ Fourier-transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-vis) spectroscopy, cyclic voltammetry, and real-time differential electrochemical mass spectrometry (DEMS), we examine how the nature of the electrolyte anion affects the CO 2 release onset potentials. The time-resolved analyses reveal that Cl⁻ ions are more effective in releasing Cu ions and hence CO 2 than nitrate or perchlorate. Molecular dynamics simulations show that strong surface Cu–Cl interactions likely facilitate favorable CO 2 and carbamate adsorption kinetics. We expect that this study paves the way for broader use of interfacial in-situ analytics in electrified CO 2 capture and release.