Tannic Acid‐Assisted Nickel‐Modified Self‐Supported Copper Nanowire Electrodes for Sustainable Electrocatalytic Nitrate‐to‐Ammonia Conversion

ABSTRACT

Electrocatalytic nitrate reduction to ammonia offers a sustainable route for nitrate pollution control and nitrogen resource recovery. Herein, a self‐supported copper nanowire electrode is fabricated on copper foam through in situ oxidative etching and reduction, followed by tannic acid‐assisted nickel modification to obtain Ni‐TA/Cu NW. The interconnected copper nanowire framework increases the accessible active area, while tannic acid introduces oxygen‐containing coordination sites that regulate the surface microenvironment and promote metal species dispersion. Structural characterizations confirm that Ni‐related species and tannic acid‐derived functional groups are introduced on the Cu nanowire surface without destroying the conductive framework. The Ni‐TA/Cu NW electrode exhibits excellent nitrate‐to‐ammonia performance in neutral electrolyte, achieving an ammonia yield rate of 5.7360 mg h ⁻¹ cm ⁻² at −0.64 V versus RHE and a Faradaic efficiency of 98.16% at −0.54 V versus RHE. It also suppresses nitrite accumulation and maintains stable performance during cycling tests. This work provides an effective interface‐engineering strategy for copper‐based self‐supported electrodes toward sustainable nitrate conversion.