Insights into lattice oxygen and strains of oxide-derived copper for ammonia electrosynthesis from nitrate.

Wu, Qinyue; Fan, Xinfei; Shan, Bing; Qi, Liang; Quan, Xie; Liu, Yanming · Nat Commun · 2025

basic_science · Level V

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Abstract

Electrocatalytic NO<sub>3</sub><sup>-</sup> reduction (eNO3RR) is a sustainable method for purification of NO<sub>3</sub><sup>-</sup> wastewater and NH<sub>3</sub> recovery. Cu-based catalysts are promising for eNO3RR, but insufficient active hydrogen (*H) supply and *NO<sub>2</sub> poison of active sites have hindered their performance, and the catalytic mechanism remains ambiguous. Here, we report oxide-derived copper nanosheet arrays (OD-Cu NSs) with residual lattice oxygen and lattice strains to enhance NH<sub>3</sub> synthesis from eNO3RR. It is efficient for NH<sub>3</sub> synthesis with high Faradaic efficiencies of 88.7-99.7% and maximum NH<sub>3</sub> yield of 6.20 mmol·h<sup>-1</sup>·cm<sup>-2</sup> at neutral solution, 10-140 mM NO<sub>3</sub><sup>-</sup> and 50-1500 mA·cm<sup>-2</sup>. Experimental and theoretical results reveal that lattice oxygen regulates the electronic structure of OD-Cu NSs and promotes *NO<sub>2</sub> conversion, while lattice strain enhances *H generation from water dissociation, resulting in the good performance for NH<sub>3</sub> synthesis. The applicability of OD-Cu NSs is proved by the high recovery of ammonia compound from eNO3RR.