Stabilizing Cu<sup>0</sup>-Cu<sup>δ+</sup> sites via ohmic contact interface engineering for ampere-level nitrate electroreduction to ammonia.

Li, Zeyu; Zheng, Ming; Yan, Chunshuang; Yang, Dongqi; Yang, Ruyu; Zhang, Chu; Liu, Hengjie; Song, Pin et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The synergistic Cu<sup>0</sup>-Cu<sup>δ+</sup> sites are found as the active sites for NH<sub>3</sub> synthesis through nitrate electroreduction reaction, but still face significant challenges in stabilizing the Cu<sup>δ+</sup> due to its self-reduction. Here we propose an Ohmic contact interface engineering strategy by loading copper nano-islands on indium hydroxide nanocubes. Attributed to the lower work function of Cu than that of In(OH)<sub>3</sub> with n-type semiconductor nature, the electrons in Cu can transfer unimpededly to In(OH)<sub>3</sub> at the interface of Ohmic junction, triggering and stabilizing polarized Cu<sup>0</sup>-Cu<sup>δ+</sup> active sites. Cu@In(OH)<sub>3</sub> sustains both high NH<sub>3</sub> yield rate (4.28 mmol h<sup>-1</sup> mg<sub>cat.</sub><sup>-1</sup>) and Faradaic efficiency (97.35%) at -0.6 V vs. RHE, while maintaining stability for at least 120 h under an Ampere-level of 800 mA cm<sup>-2</sup>. Such Ohmic contact interface engineering approach allows for simultaneously constructing and stabilizing the Cu<sup>0</sup>-Cu<sup>δ+</sup> for the electrosynthesis of ammonia, as well as other value-added chemicals relying on above active sites.