Authors
Gabriel A Cerrón-Calle, Andrea N Arias-Sanchez, Marco Flores, Manuel A Roldan, Carlos M Sánchez-Sánchez, Sergi Garcia-Segura
Published in
Angewandte Chemie (International ed. in English). Pages e6942767. Jul 02, 2026. Epub Jul 02, 2026.
Abstract
The electrochemical reduction of nitrate (ERN) to ammonia (NH3) has attracted increasing attention as a sustainable route for nitrogen recovery and green ammonia production, enabled by major advances in electrocatalyst design over the past decade. Two mechanistic pathways are generally well-recognized: direct electron transfer and a hydrogen radical (H*)-mediated mechanism. However, the latter remains difficult to quantify under practical electrochemical conditions, limiting mechanistic comparison across catalyst configurations. Herein, Ni/Co, Ni/Pt, and Ni/Pt/Co electrocatalysts were investigated to elucidate the interplay between direct and indirect ERN pathways. Quantitative electron spin resonance (ESR) measurements of H* under ERN-relevant conditions, combined with bulk electrolysis in the absence and presence of an H* scavenger, enabled direct correlation between H* availability and NH3 production. Ni/Co predominantly follows direct electron transfer, whereas Ni/Pt transitions to an H*-mediated regime above a threshold current density. In contrast, Ni/Pt/Co exhibits synergistic behavior in which both pathways coexist. Moreover, the H* role varies with electrocatalyst chemical composition, facilitating either NO3 - activation or NO2 - hydrogenation. These findings establish a quantitative framework for resolving H*-mediated contribution in ERN and provide mechanistic design principles applicable to other electrocatalytic hydrogenation reactions.
PMID:
42390830
Bibliographic data and abstract were imported from PubMed on 02 Jul 2026.
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