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Visualization of CO2 electrolysis using optical coherence tomography

Nature Chemistry (2024)Cite this article

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Abstract

Electrolysers offer an appealing technology for conversion of CO2 into high-value chemicals. However, there are few tools available to track the reactions that occur within electrolysers. Here we report an electrolysis optical coherence tomography platform to visualize the chemical reactions occurring in a CO2 electrolyser. This platform was designed to capture three-dimensional images and videos at high spatial and temporal resolutions. We recorded 12 h of footage of an electrolyser containing a porous electrode separated by a membrane, converting a continuous feed of liquid KHCO3 to reduce CO2 into CO at applied current densities of 50–800 mA cm−2. This platform visualized reactants, intermediates and products, and captured the strikingly dynamic movement of the cathode and membrane components during electrolysis. It also linked CO production to regions of the electrolyser in which CO2 was in direct contact with both membrane and catalyst layers. These results highlight how this platform can be used to track reactions in continuous flow electrochemical reactors.

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Fig. 1: The eOCT platform used to image CO2 electrolysis in operando in 3D as a function of time.
Fig. 2: High-resolution eOCT and SEM images of the electrolyser components.
Fig. 3: Polarization and intensity images showing the generation of discrete CO2 and CO bubbles in a CO2 electrolyser taken by eOCT.
Fig. 4: Phase-distribution images showing the distribution of CO2(g), H2(g) and CO(g) after 3 h of electrolysis.
Fig. 5: The TPCs quantified by the eOCT platform at various operational and system conditions.
Fig. 6: Effect of pulsed-current on CO formation rates (jCO, grey), CO production observed in images captured by the eOCT (green) and number of TPCs (dark purple).

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Data availability

The data supporting the findings of this study are available within the paper and its Supplementary Information files. We have prepared a data set related to the main manuscript available at https://doi.org/10.5281/zenodo.10531471. This study produced >2 TB of visualization data. Should any additional raw data files be needed in another format they are available from the corresponding author upon reasonable request.

Code availability

All code for data cleaning and analysis associated with the current submission is available at https://doi.org/10.5281/zenodo.10531471. All code folders contain a detailed readme file to explain their use.

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Acknowledgements

We thank J. Madden (University British Columbia), Y. Bengio (University of Montreal), E. Ilic (University British Columbia), V. Schmidt, A. Hernandez Garcia, O. Boussif and D. Yasafovad for useful discussions and suggestions. The authors are grateful to the Max Planck-UBC-UTokyo Center for Quantum Materials; the Canada First Research Excellence Fund, Quantum Materials and Future Technologies Program; the Canadian Natural Sciences and Engineering Research Council (RGPIN-2018-06748, C.P.B.), Canadian Foundation for Innovation (229288, C.P.B.), Canadian Institute for Advanced Research (BSE-BERL-162173, C.P.B.); and the Canada Research Chairs for financial support. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. SEM imaging was performed in the Centre for High-Throughput Phenogenomics at the University of British Columbia, a facility supported by the Canada Foundation for Innovation, British Columbia Knowledge Development Foundation, and the UBC Faculty of Dentistry.

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  1. These authors contributed equally: Xin Lu, Chris Zhou.

Authors and Affiliations

  1. Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada

    Xin Lu, Abhishek Soni, Shaoxuan Ren, Tengxiao Ji & Curtis P. Berlinguette

  2. Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, British Columbia, Canada

    Chris Zhou

  3. Department of Materials Engineering, The University of British Columbia, Vancouver, British Columbia, Canada

    Chris Zhou & Frank Ko

  4. Stewart Blusson Quantum Matter Institute, The University of British Columbia, Vancouver, British Columbia, Canada

    Chris Zhou, Roxanna S. Delima, David J. Dvorak, Addie Bahi, Frank Ko & Curtis P. Berlinguette

  5. Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, British Columbia, Canada

    Roxanna S. Delima, Eric W. Lees & Curtis P. Berlinguette

  6. Canadian Institute for Advanced Research, Toronto, Ontario, Canada

    Curtis P. Berlinguette

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Contributions

C.P.B. supervised the project. F.K. is the direct supervisor of C.Z. X.L., C.Z., D.J.D., A.S. and A.B. performed experiments and data processing. X.L, R.S.D., C.Z., A.S., E.W.L., S.R., T.J. and C.P.B. wrote the manuscript. All authors discussed the results and assisted with manuscript preparation.

Corresponding author

Correspondence to Curtis P. Berlinguette.

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Supplementary information

Supplementary Information

Captions for Supplementary Movies 1–8, Figs. 1–26 and Table 1, and references.

Supplementary Video 1

Time-resolved visualization of the eOCT intensity in the X–Z plane of the CO2 electrolyser during 12 h of electrolysis at 100 mA cm−2.

Supplementary Video 2

3D rotational view of the cathode captured by eOCT during electrolysis at a current density of 100 mA cm−2.

Supplementary Video 3

Time-resolved visualization of the eOCT intensity in the X–Z plane of the CO2 electrolyser when the current density is switched from 0 to 100 mA cm−2. Bubbles are formed at the membrane and cathode which causes separation of the two layers during electrolysis.

Supplementary Video 4

Time-resolved visualization of eOCT of a control experiment used to quantify CO2 bubbles.

Supplementary Video 5

Time-resolved visualization of the eOCT intensity in the X–Z plane of the CO2 electrolyser of single CO2 bubble dynamics at the membrane surface at a current density of 100 mA cm−2. This movie tracks the classical bubble evolution microprocesses including nucleation, necking and collapse.

Supplementary Video 6

Time-resolved visualization of the eOCT polarization in the X–Z plane of the CO2 electrolyser of single CO2 bubble dynamics at the membrane surface at a current density of 100 mA cm−2. This movie tracks the classical bubble evolution microprocesses including nucleation, necking and collapse.

Supplementary Video 7

The phase-distribution movie showing the presence of CO2(g) pathway at the cathode, continuously supplying CO2(g) to form CO(g).

Supplementary Video 8

The signal similarities between reactants and products for CO2RR and HER with time shifts applied.

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Lu, X., Zhou, C., Delima, R.S. et al. Visualization of CO2 electrolysis using optical coherence tomography. Nat. Chem. (2024). https://doi.org/10.1038/s41557-024-01465-5

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