Abstract
The electrochemical reduction of CO2 to oxalate has emerged as a promising pathway for both carbon utilization and negative-emission strategies, as it couples renewable electricity with the production of a high-value platform chemical. In this work, we investigated the electroreduction of CO2 in a novel designed-flow reactor employing stainless steel cathode in an acetonitrile medium. The reactor design was evaluated by varying electrode spacing (0.5, 1, and 2 mm) and scaling electrode area (from 10 mm2 to 656 mm²), aiming to enhance mass transport and reduce ohmic losses. Faradaic efficiencies up to 72% and current densities above 130 mA cm−2 were achieved, which surpass previously reported results for flow systems. Notably, scaling up to 656 mm² electrodes maintained competitive efficiency while significantly improving oxalate production rates. These results demonstrate one of the few successful demonstrations of CO2-to-oxalate conversion in a continuous-flow configuration, highlighting the potential of reactor engineering approaches for advancing scalable and environmentally benign CO2 electroreduction technologies.
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The datasets generated during the current study are available from the corresponding author on reasonable request.
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Funding
The authors gratefully acknowledge support of the RCGI – Research Centre for Greenhouse Gas Innovation (23.1.8493.1.9), hosted at the University of São Paulo (USP) and sponsored by FAPESP – São Paulo Research Foundation (2020/15230-5) and Shell Brasil, and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&DI levy regulation. We also thank FAPESP for the support through grants 2023/09823-1, 2017/22130-6, 2024/08727-1, 2022/14049-0, and 2020/01177-5. ECNS would like to thank CNPq for the support under project No. 304508/2023-3.
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DD carried out the experiments, data analysis, and interpretation, experimental design, and wrote the main manuscript text. BNR assisted in the experiments, data analysis, and interpretation and elaborated on Figure 01. LNBSR contributed to reactor designs and to the elaboration of Figure 01. ECNS contributed to manuscript elaboration. JRM contributed to fundraising and project management. TL conceived the project, supervised the work, contributed to fundraising, designed experiments, conducted data analysis and interpretation, and managed the project. All authors reviewed the manuscript.
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Dionisio, D., Narváez-Romo, B., Ribeiro, L.N.B.S. et al. Scalable electrochemical CO2 reduction to oxalate in a continuous flow reactor. Sci Rep (2026). https://doi.org/10.1038/s41598-026-43540-6
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DOI: https://doi.org/10.1038/s41598-026-43540-6
