Abstract
Geen ammonia synthesis through electrochemical nitrate reduction (e-NO3R) using cost-effective Co-based catalysts is promising, but the inevitable structural evolution induced by reductive potentials compromises long-term stability and hinders practical implementation. Focusing on β-Co(OH)2, which serves as the active phase in e-NO3R systems, this work combines experimental analysis and computational studies to reveal a dynamic surface *OH evolution process: *OH cleavage under negative potentials and *OH generation by the dissociation of NO3-. Notably, Ru nanoparticles anchored on β-Co(OH)2 nanosheets promote structural evolution by facilitating *OH cleavage and generation, thereby sustaining a highly active and selective OH-terminated surface. Simultaneously, Ru provides moderate *H adsorption, accelerates the conversions from NO3− to NO2− and from NO2− to NH3, and thus enhances ammonia synthesis. The optimized Co(OH)2-Ru catalyst achieves an ammonia yield of 98 ± 0.91 mg·h-1·cm-2 with a Faradaic efficiency (FE) of 97.7 ± 0.90 % at −0.7 V versus reversible hydrogen electrode (vs. RHE), while maintaining NH3 FEs above 95% across a broad potential window. This work elucidates structural evolution dynamics, offering a design principle for robust electrocatalysts.
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Acknowledgements
Dr. H. Pan acknowledges support from the Science and Technology Development Fund (FDCT) from Macau SAR (0050/2023/RIB2, 0023/2023/AFJ, 0002/2024/TFP, and 0111/2022/A2), and Multi-Year Research Grants (MYRG-GRG2025-00007-IAPME and MYRG-GRG2024-00038-IAPME) from the University of Macau. Dr. W. F. Ip acknowledges support from the Science and Technology Development Fund (0087/2024/AFJ). The DFT calculations are performed at the High-Performance Computing Cluster (HPCC) of the Information, Communication Technology Office (ICTO) at the University of Macau.
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D.L., H.B. and M.C. contributed equally to this manuscript. D.L. and H.P. conceived the idea. D.L. and M.C. contributed to the experimental design, material synthesis, electrochemical measurements, data analysis, TEM and XAFS characterization, and drafting of the initial manuscript. H.B. and D.L. designed and performed the theoretical calculations and also contributed to writing the initial draft. S.P., J.K., L.L., Z.F., and C.L. assisted with XRD and XPS characterization and contributed to editing the draft. W.I. and H.P. provided overall supervision of the project and revised the manuscript. All authors discussed the results and commented on the manuscript.
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Liu, D., Bai, H., Chen, M. et al. Unravelling the Ru-promoted dynamic evolution of Cobalt hydroxide during nitrate reduction towards ammonia production. Nat Commun (2026). https://doi.org/10.1038/s41467-026-70531-y
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DOI: https://doi.org/10.1038/s41467-026-70531-y
