Interfacial Confinement-Programmed Hydrogen Spillover on Ag/CoNiS Boosts Nitrate-to-Ammonia Electrosynthesis.
basic_science · Level V
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- Record sourced from PubMed, PMID 42370544.
- Also identified by DOI 10.1002/adma.73885.
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Abstract
Electrochemical nitrate reduction (NO<sub>3</sub>RR) under ambient conditions offers a sustainable route for ammonia (NH<sub>3</sub>) synthesis; however, its efficiency is restricted by the kinetic mismatch between water dissociation and nitrate hydrogenation. Here, we design Ag/CoNiS heterostructures in which Ag loading density programs interfacial confinement to regulate hydrogen spillover from CoNiS water-activation domains to Ag-associated nitrate/nitrogen oxide (NO<sub>x</sub>) intermediates, thereby coupling <sup>*</sup>H generation, relay, and deep nitrate hydrogenation. The optimized Ag<sub>M</sub>/CoNiS achieves an NH<sub>3</sub> yield of 22.31 mg h<sup>-1</sup> cm<sup>-2</sup> with 99.13% Faradaic efficiency. In situ Raman, distribution of relaxation times (DRT) analysis, hydrogen/deuterium (H/D) isotope experiments, and tert-butanol (TBA) perturbation tests reveal that the confined Ag-CoNiS interface regulates interfacial water and establishes a balanced <sup>*</sup>H supply-consumption regime, thereby suppressing competing hydrogen evolution. Density functional theory (DFT) calculations further show that Ag facilitates nitrate deoxygenation, whereas excessive Ag coverage weakens Co/Ni-centered water activation, explaining the volcano-type activity trend. Coupling NO<sub>3</sub>RR with the sulfide oxidation reaction (SOR) further enables a low-voltage NO<sub>3</sub>RR||SOR electrolyzer, requiring only 0.70 V at 50 mA cm<sup>-2</sup> for energy-saving co-production of ammonia and sulfur.