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Integration of thermochemical water splitting with CO₂ direct air capture

Brady, Casper and Davis, Mark E. and Xu, Bingjun (2019) Integration of thermochemical water splitting with CO₂ direct air capture. Proceedings of the National Academy of Sciences of the United States of America, 116 (50). pp. 25001-25007. ISSN 0027-8424. PMCID PMC6911180. doi:10.1073/pnas.1915951116.

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Renewable production of fuels and chemicals from direct air capture (DAC) of CO₂ is a highly desired goal. Here, we report the integration of the DAC of CO₂ with the thermochemical splitting of water to produce CO₂, H₂, O₂, and electricity. The produced CO₂ and H₂ can be converted to value-added chemicals via existing technologies. The integrated process uses thermal solar energy as the only energy input and has the potential to provide the dual benefits of combating anthropogenic climate change while creating renewable chemicals. A sodium–manganese–carbonate (Mn–Na–CO₂) thermochemical water-splitting cycle that simultaneously drives renewable H₂ production and DAC of CO₂ is demonstrated. An integrated reactor is designed and fabricated to conduct all steps of the thermochemical water-splitting cycle that produces close to stoichiometric amounts (∼90%) of H₂ and O₂ (illustrated with 6 consecutive cycles). The ability of the cycle to capture 75% of the ∼400 ppm CO₂ from air is demonstrated also. A technoeconomic analysis of the integrated process for the renewable production of H₂, O₂, and electricity, as well as DAC of CO₂ shows that the proposed scheme of solar-driven H₂ production from thermochemical water splitting coupled with CO₂ DAC may be economically viable under certain circumstances.

Item Type:Article
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URLURL TypeDescription Information CentralArticle
Davis, Mark E.0000-0001-8294-1477
Xu, Bingjun0000-0002-2303-257X
Additional Information:© 2019 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). Contributed by Mark E. Davis, October 18, 2019 (sent for review September 13, 2019; reviewed by Christopher W. Jones and Steven Suib). PNAS first published November 21, 2019. C.B. and B.X. acknowledge support from the University of Delaware Research Foundation UDRF-SI 2017. Data availability: All data are available in the main text and SI Appendix. Author contributions: C.B., M.E.D., and B.X. designed research; C.B. performed research; C.B., M.E.D., and B.X. analyzed data; and C.B., M.E.D., and B.X. wrote the paper. Reviewers: C.W.J., Georgia Tech; and S.S., University of Connecticut. The authors declare no competing interest. This article contains supporting information online at
Funding AgencyGrant Number
University of DelawareUDRF-SI 2017
Subject Keywords:sodium manganese oxide; process integration; technoeconomic analysis
Issue or Number:50
PubMed Central ID:PMC6911180
Record Number:CaltechAUTHORS:20191122-112403919
Persistent URL:
Official Citation:Integration of thermochemical water splitting with CO2 direct air capture. Casper Brady, Mark E. Davis, Bingjun Xu. Proceedings of the National Academy of Sciences Dec 2019, 116 (50) 25001-25007; DOI: 10.1073/pnas.1915951116
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100019
Deposited By: Tony Diaz
Deposited On:22 Nov 2019 20:42
Last Modified:16 Feb 2022 22:56

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