Electrodeposited copper–nickel nanoparticles as highly efficient electrocatalysts for nitrate reduction to ammonia

Abstract

Utilizing renewable electricity to convert nitrate (NO₃⁻) into ammonia (NH₃) represents a promising research direction because this reaction can not only remove excessive and poisonous NO₃⁻ from wastewater to assuage environmental problems but also simultaneously generate NH₃. However, eight electrons are involved in this electroreduction reaction which highlights that genuinely designing electrocatalysts to exclusively synthesize NH₃ without side products is highly desirable. In this study, copper–nickel nanoparticles on Ti mesh prepared by the electrodeposition method were verified as superior electrocatalysts toward electrochemical reduction of NO₃⁻ with an onset potential of 0 V vs. RHE. A large NH₃ yield rate of 5644 μg h⁻¹ cm⁻² with a corresponding faradaic efficiency of 93.1% was achieved in 0.1 M KOH with 0.1 M NO₃⁻. Subsequent electrochemical tests in a low-concentration NO₃⁻-containing solution (0.01 M NO₃⁻ in 0.1 M KOH) and simulated wastewater consistently confirmed the phenomenal performances and broad applications of the as-prepared electrocatalysts.