Cooperative effects associated with high electrolyte concentrations in driving the conversion of CO₂ to C₂H₄ on copper
Creators
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1.
California Institute of Technology
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2.
University of Colorado Boulder
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3.
National Renewable Energy Laboratory
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4.
Stanford University
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5.
SLAC National Accelerator Laboratory
Abstract
Compared to a conventional electrolyte concentration of 1 M HCOOK, the use of a highly concentrated 7.1 M HCOOK electrolyte increases the Faradaic efficiency (FE) ratio of C2H4/CO from 2.2 ± 0.3 to 18.3 ± 4.8 at −1.08 V vs. reversible hydrogen electrode (RHE) on a Cu gas-diffusion electrode. Based on electrochemical analysis and ab initio molecular dynamics (AIMD) simulation, the identity and concentration of the cation and anion play more important roles in controlling the CO2R reaction pathway than the bulk CO2 solubility and the bulk pH of electrolytes. In situ attenuated reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) suggests that, unlike 1 M HCOOK, the ∗CO-bridge-binding mode on Cu is dominant in 7.1 M HCOOK electrolyte, which potentially results in less CO release and higher yield of C2H4. This study demonstrates that although we can tailor the electrolyte composition to shift product selectivity, the factors that control the product selectivity are numerous and cannot be distilled down into one correlated property-reactivity relationship.
Acknowledgement
This work was supported by the Liquid Sunlight Alliance (LiSA), which is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DE-SC0021266. We gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute at Caltech. We thank the Beckman Institute for their support of the X-Ray Crystallography Facility at Caltech. K.A.S. acknowledges support from the David and Lucile Packard Foundation through the Packard Fellowship for Science and Engineering, the Camille & Henry Dreyfus Foundation, and the Alfred P. Sloan Foundation. The XPS data were collected at the Molecular Materials Research Center in the Beckman Institute at Caltech. The authors thank Jake M. Evans for the helpful discussions regarding the XPS data collection. J.E.M. acknowledges a graduate fellowship through the National Science Foundation Graduate Research Fellowship under grant no. DGE-1656518. This work used expanse at San Diego Supercomputer Center through allocation DMR160114 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by US National Science Foundation grants 2138259, 2138286, 2138307, 2137603, and 2138296.
Copyright and License
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Supplemental Material
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Document S1. Figures S1–S22 and Tables S1–S6.
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Data Availability
Data supporting the findings of this work are provided in the supplemental information. All additional information and data are available upon reasonable request.
Contributions
S.L. performed electrochemistry experiments. Y.F. conducted in situ ATR-SEIRAS experiments. S.K. and M.Y.Y. performed molecular dynamics simulations. A.E.B. conducted laser-scanning confocal microscopy. W.N. performed NMR testing. J.E.M. measured CO2 solubility. Z.W.B.I. collected XRD data. B.C.L performed XPS experiments. T.F.J., H.A.A., W.A.G., and W.A.S. supervised the project. K.A.S. ideated and supervised the project. All authors analyzed data and prepared the manuscript.
Conflict of Interest
The authors declare no competing interests.
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Additional details
Funding
- Office of Basic Energy Sciences
- Fuels from Sunlight Hub DE-SC0021266
- David and Lucile Packard Foundation
- Packard Fellowship for Science and Engineering
- Camille and Henry Dreyfus Foundation
- Alfred P. Sloan Foundation
- National Science Foundation
- Graduate Research Fellowship DGE-1656518
- National Science Foundation
- 2138259
- National Science Foundation
- 2138286
- National Science Foundation
- 2138307
- National Science Foundation
- 2137603
- National Science Foundation
- 2138296
- Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support
- DMR160114
Dates
- Accepted
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2025-03-11Accepted
- Available
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2025-04-04Published online