Unravelling the Ru-promoted dynamic evolution of Cobalt hydroxide during nitrate reduction towards ammonia production.
basic_science · Level V
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- Record sourced from PubMed, PMID 41844587.
- Also identified by DOI 10.1038/s41467-026-70531-y.
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Abstract
Geen ammonia synthesis through electrochemical nitrate reduction (e-NO<sub>3</sub>R) 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)<sub>2</sub>, which serves as the active phase in e-NO<sub>3</sub>R 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 NO<sub>3</sub><sup>-</sup>. Notably, Ru nanoparticles anchored on β-Co(OH)<sub>2</sub> 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 NO<sub>3</sub><sup>-</sup> to NO<sub>2</sub><sup>-</sup> and from NO<sub>2</sub><sup>-</sup> to NH<sub>3</sub>, and thus enhances ammonia synthesis. The optimized Co(OH)<sub>2</sub>-Ru catalyst achieves an ammonia yield of 98 ± 0.91 mg·h<sup>-1</sup>·cm<sup>-2</sup> with a Faradaic efficiency (FE) of 97.7 ± 0.90 % at -0.7 V versus reversible hydrogen electrode (vs. RHE), while maintaining NH<sub>3</sub> FEs above 95% across a broad potential window. This work elucidates structural evolution dynamics, offering a design principle for robust electrocatalysts.