Electronic structure modulation of Ni-decorated Cu nanowire electrode for efficient nitrate-to-ammonia conversion in neutral media

A Cu foam supported Ni Cu nanowire electrode (Ni-CuNW) was fabricated and optimized. • Ni species modulated electronic structure of Cu and redistributed surface electron. • High-efficient NO 3 − to NH 3 conversion was achieved in neutral-media conditions. • Ni-CuNW enabled ~100% NO 3 − removal with 99.5% NH 4 + -N selectivity and 95.5% NH 3 FE. • FE for NH 3 production maintained above 90% across various NO 3 − concentrations. Electrocatalytic nitrate-to-ammonia conversion has emerged as a pivotal green technology that simultaneously enables waste valorization and sustainable ammonia production, offering a promising alternative to the energy-intensive Haber-Bosch process. Herein, we reported a highly efficient Ni-decorated Cu nanowire electrode (Ni-CuNW) that exhibited remarkable electrocatalytic activity under challenging neutral media, which typically suffers from insufficient H* supply and severe competition from the hydrogen evolution reaction (HER). The optimized electrode achieved near complete nitrate removal with 99.5% NH 4 + -N selectivity and 95.5% Faradaic efficiency (FE) for NH 3 production during treatment of nitrate-laden wastewater (50 mg L −1 NO 3 − -N), and maintained an NH 3 FE of 90% even in high-concentration wastewater containing 2000 mg L −1 NO 3 − -N. An integrated reactor incorporating an in-situ ammonia recovery unit was constructed, and over 95% nitrate removal and 85% NH 3 recovery were achieved under various nitrate concentrations, demonstrating its robust practical applicability. Mechanism studies revealed that the superior performance originated from the incorporation of Ni(OH) 2 species, which modulated the electronic structure of Cu and induced surface electron redistribution. This electronic structure modulation accelerated interfacial electron transfer and strengthened the adsorption of NO 3 − and nitrogen-containing intermediates. Concurrently, Ni species incorporation selectively suppressed the competing HER at active sites, thereby endowing the Ni-CuNW electrode with exceptional FE for NH 3 production. This work presented an efficient and scalable strategy for synthesizing advanced electrocatalysts suitable for both wastewater remediation and sustainable ammonia production. Download: Download high-res image (140KB) Download: Download full-size image