Trade-off between redox potential and strength of electrochemical CO2 capture in quinones

07 March 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Electrochemical carbon dioxide capture has recently emerged as a promising alternative approach to conven- tional energy-intensive carbon capture methods. The most common electrochemical capture approach is to employ redox-active molecules such as quinones. Upon electrochemical reduction, quinones become activated for the chemical capture of CO2. The main disadvantage of this method is the possibility of side-reactions with oxygen, which is present in almost all gas mixtures of interest for carbon capture. This issue can potentially be mitigated by fine-tuning redox potentials through the introduction of electron-withdrawing groups on the quinone ring. In this article, we investigate the thermodynamics of the electron transfer and chemical steps of CO2 capture in different anthraquinone derivatives with a range of substituents. By combining density functional theory calculations and cyclic voltammetry experiments, we discover a trade-off between redox potentials and the strength of CO2 capture. We show that redox potentials can readily be tuned to more positive values to impart stability to oxygen, but as a consequence, significant decreases in CO2 binding free energies are observed. This trade-off must be taken into consideration for the design of improved redox active molecules for electrochemical CO2 capture.


carbon capture
carbon dioxide capture
electrochemical carbon capture
CO2 capture
redox potentials
cyclic voltammetry
density functional theory

Supplementary materials

Supplementary Information
Supplementary Information for “Trade-off between redox potential and strength of electrochemical CO2 capture in quinones”. This includes: Orbital analysis of species in EECC for AQ, Hydrogen bonding in OH case, Substitutions of Me-series, Going from gas phase to solution phase, Trade-off in BQ F series, CV of AQ under O2.


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