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

TL;DR

This study explores how different anions affect the efficiency of electrochemical CO2 capture and release processes, revealing that chloride ions are more effective than others.

Contribution

The study provides molecular-level insights into how anions influence CO2 release kinetics in electrochemical systems.

Findings

Chloride ions are more effective than nitrate or perchlorate in facilitating CO2 release via copper ion release.

Strong surface interactions between copper and chloride ions enhance CO2 and carbamate adsorption kinetics.

In-situ analytics can guide the design of efficient electrochemical CO2 capture systems.

Abstract

Ambient electrochemical CO2 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 CO2 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 CO2 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 CO2 release onset potentials. The time-resolved analyses reveal that Cl⁻ ions are more effective in releasing Cu ions and hence CO2 than nitrate or perchlorate. Molecular dynamics simulations show that strong surface Cu–Cl interactions likely facilitate favorable CO2 and carbamate adsorption kinetics. We expect that this study paves the way for broader use of interfacial in-situ analytics in electrified CO2 capture and release.

Electrochemical amine regeneration offers a renewable, low-temperature pathway for CO2 capture. Here, the authors reveal how anions regulate interfacial copper redox kinetics that control electrochemical CO2 release using in-situ spectroscopic and computational analyses.

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