Langmuir-Hinshelwood pathway enables 1000-h stable nitrate-to-ammonia electroreduction at 1 A cm<sup>-2</sup>.
basic_science · Level V
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- Record sourced from PubMed, PMID 42265120.
- Also identified by DOI 10.1038/s41467-026-74321-4.
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Abstract
Achieving stable and selective electrocatalytic nitrate reduction (NO<sub>3</sub>RR) at high current densities demands a fundamental understanding of the hydrogenation mechanism. We demonstrate that alloying cobalt with ruthenium (RuCo) switches the dominant hydrogenation pathway from the Eley-Rideal (E-R) mechanism, involving solvated protons, to the Langmuir-Hinshelwood (L-H) mechanism, utilizing adsorbed protons. Microkinetic modeling, in situ spectroscopy and density functional theory (DFT) calculations reveal that the competitive E-R pathway on pure Co causes sluggish hydrogenation kinetics and low Faradaic efficiency. In contrast, the L-H pathway on RuCo sustains high hydrogen coverage (θ<sub>H</sub> ≈ 0.45), enabling efficient hydrogen-atom transfer for high-rate and deep hydrogenation. Leveraging this mechanistic insight, we achieve a satisfactory ammonia yield rate of 135.53 ± 1.18 mg h<sup>-1</sup> cm<sup>-2</sup> with 100% Faradaic efficiency and robust 1000-h stability at 1 A cm⁻². This work provides critical understanding of electrochemical hydrogenation pathways for designing efficient catalysts operating under industrially relevant conditions.