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Redox-tunable Lewis bases for electrochemical carbon dioxide capture


Carbon capture is considered a critical means for climate change mitigation. However, conventional wet chemical scrubbing utilizing sp3 amines suffers from high energy consumption, corrosion and sorbent degradation, motivating the search for more efficient carbon dioxide separation strategies. Here, we demonstrate a library of redox-tunable Lewis bases with sp2-nitrogen centres that can reversibly capture and release carbon dioxide through an electrochemical cycle. The mechanism of the carbon capture process is elucidated via a combined experimental and computational approach. We show that the properties of these Lewis base sorbents can be fine-tuned via molecular design and electrolyte engineering. Moreover, we identify a bifunctional azopyridine base that holds promise for electrochemically mediated carbon capture, exhibiting >85% capacity utilization efficiency over cycling in a flow system under 15% carbon dioxide with 5% oxygen. This work broadens the structural scope of redox-active carbon dioxide sorbents and provides design guidelines on molecules with tunable basicity under electrochemical conditions.

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Fig. 1: Conventional sp3 nitrogen bases and redox-tunable sp2 nitrogen bases for carbon capture.
Fig. 2: A broad chemical space of redox-tunable sp2 nitrogen bases for EMCC.
Fig. 3: The seven elementary reaction steps (ECEC mechanism) considered in the DFT calculations.
Fig. 4: Molecular and electrolyte engineering concepts to optimize the CO2 separation performance of redox-tunable Lewis base sorbents.
Fig. 5: CO2 separation performance in an EMCC flow cell with AzPy.
Fig. 6: CO2 separation performance in an EMCC flow cell with AzPy in the presence of oxygen impurity.

Data availability

The data generated or analysed during this study are included in the published article and its Supplementary Information file. Source data are provided with this paper.


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Yayuan Liu. and T.A.H. acknowledge support from the National Science Foundation (grant number 2029442). Yayuan Liu and X.L. acknowledge support from the Johns Hopkins University and American Chemical Society Petroleum Research Fund (65626-DNI4). Yuanyue Liu acknowledges support from the National Science Foundation (grant numbers 1900039 and 2029442), American Chemical Society Petroleum Research Fund (60934-DNI6) and Welch Foundation (grant number F-1959-20210327). For the calculations, we used computational resources at the Extreme Science and Engineering Discovery Environment, Texas Advanced Computing Center, Argonne National Laboratory and Brookhaven National Laboratory. We thank K. M. Diederichsen, H. Seo and E. Wenbo Zhao for helpful discussions.

Author information

Authors and Affiliations



Yayuan Liu conceived of the project and designed the experiments. Yayuan Liu and X.L. carried out the experiments and analysed the data. X.Z. performed the DFT calculations. Yayuan Liu, Yuanyue Liu and T.A.H. supervised the project. Yayuan Liu, X.L. and X.Z. wrote the paper. All authors discussed the results and revised or commented on the manuscript.

Corresponding authors

Correspondence to Yuanyue Liu, T. Alan Hatton or Yayuan Liu.

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Nature Energy thanks Rajeev Assary and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–21, Tables 1–9 and Notes 1–4.

Source data

Source Data Fig. 2

Cyclic voltammetry data for panels a–f.

Source Data Fig. 4

Cyclic voltammetry data for panels a–c and e.

Source Data Fig. 5

Time versus CO2 concentration data for each capture–release cycle.

Source Data Fig. 6

Time versus CO2 concentration data for each capture–release cycle and capture–release voltage profiles for panel d.

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Li, X., Zhao, X., Liu, Y. et al. Redox-tunable Lewis bases for electrochemical carbon dioxide capture. Nat Energy 7, 1065–1075 (2022).

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