Direct air capture of CO2via cyclic viologen electrocatalysis

Shijie Liu, Jinqiang Zhang, Feng Li, Jonathan P. Edwards, Yurou Celine Xiao, Dongha Kim, Panagiotis Papangelakis, Jiheon Kim, David Elder, Phil De Luna, Mengyang Fan, Geonhui Lee, Rui Kai Miao, Tanushree Ghosh, Yu Yan, Yuanjun Chen, Yong Zhao, Zunmin Guo, Cong Tian, Peihao LiYi Xu*, Edward H. Sargent*, David Sinton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Electrochemical direct air capture (DAC) can leverage renewable electricity to reduce atmospheric CO2 levels via energy-efficient organic redox couples. However, current organic systems are threatened by oxidative degradation when explosed to air. In this work, we propose an electrochemical process to regenerate hydroxide absorbents via cyclic viologen electrocatalysis (CVE). This strategy isolates the redox-active viologens from the alkaline absorbents to avoid oxidative degradation and vaporization loss. Tuning the viologen substituent is needed to facilitate fast reaction kinetics in the electric fields present under reductive and oxidative environments. We show that di-polar viologens, which contain both positively and negatively charged groups, can overcome electric field repulsion during reduction and oxidation. We demonstrate a minimum work of 0.82 GJ per tCO2, calculated based on the cyclic voltammetry redox potentials, and a work as low as 3.8 GJ per tCO2 in a practical two-electrolyser CVE configuration with over 200 hours of stable operation.

Original languageEnglish (US)
Pages (from-to)1266-1278
Number of pages13
JournalEnergy and Environmental Science
Issue number3
StatePublished - Jan 10 2024
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution

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