NiWO4 nanoparticles with oxygen vacancies: high-efficiency electrosynthesis of ammonia with selective reduction of nitrite

Abstract

Electrochemical reduction of nitrite (NO₂⁻RR) is a promising research direction for removing environmental pollutants NO₂⁻ from wastewater and generating value-added ammonia (NH₃). However, NO₂⁻RR kinetic reactivity is slow and requires high-efficient electrocatalysts. In the present study, we report C-NiWO₄ nanoparticles grown on nickel foam as efficient catalysts. The NH₃ yield of C-NiWO₄/NF in 0.1 M NaOH containing 0.1 M NO₂⁻ was 10 974.36 μg h⁻¹ cm⁻² at −0.4 V with a Faraday efficiency of 97.6%. Notably, a Zn–NO₂⁻ battery with a C-NiWO₄/NF as cathode has a high peak power density of 5.55 mW cm⁻² and provides a simultaneous NH₃ yield of 2194.54 μg h⁻¹ cm⁻². In addition, theoretical calculations revealed the NO₂⁻RR mechanism of C-NiWO₄/NF.