Hydroxyl-rich nanocavities on perovskite enable nearly barrierless intramolecular hydrogen transfer for nitrate electroreduction to ammonia.

Xu, Mingkai; Wang, Ruizhao; Wang, Zaixing; Tang, Zheng; Huang, Wei-Hsiang; Tan, Wang; Yuan, Lingjie; Tao, Huanhuan et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Electrocatalytic nitrate reduction to ammonia (NITRR) provides a sustainable avenue for simultaneous nitrate mitigation and ammonia synthesis, but the sluggish surface hydrogen migration during NITRR remains a major bottleneck. Here, we show a barrierless hydrogen transfer pathway along intramolecular hydrogen bonds between hydroxyls of hydroxyl-rich nanocavities for efficient nitrate electroreduction to ammonia. This nanocavity is constructed via electrochemical reduction-assisted selective Sr ions leaching on the La<sub>0.4</sub>Sr<sub>0.6</sub>FeO<sub>3-δ</sub> perovskites. Combined experimental and theoretical investigations reveal that the nanocavity features nanocavity-like architecture with hydroxyl-enriched walls, boosting active hydrogen generating and hopping for NO<sub>3</sub><sup>-</sup> hydrogenation. Benefiting from such unusual intramolecular hydrogen transfer, the surface nanoconcaved La<sub>0.4</sub>Sr<sub>0.6</sub>FeO<sub>3-δ</sub> achieves a Faradaic efficiency of 97.81 % and an ammonia yield rate of 51.37 mg h<sup>-1</sup> cm<sup>-2</sup> at -0.8 V versus reversible hydrogen electrode (RHE), surpassing nanocavity-free counterpart and ranking among superior NITRR catalysts. Ampere-level current density of nitrate-to-ammonia conversion are further realized in a renewable-energy-powered electrolyzer at a very low cell voltage of 2.23 V. Techno-economic analysis underscores dual benefits of this process including economic viability in ammonia synthesis and environmental impact in nitrate remediation.