Metal–organic framework derived Co–NC for electrocatalytic reduction of nitrate to ammonia

Abstract

The electrochemical synthesis of ammonia (NO₃RR) offers a green and sustainable alternative to the traditional Haber–Bosch process, enabling ammonia production under environmentally and friendly conditions without emitting CO₂. Additionally, it effectively reduces nitrate (NO₃⁻) concentrations in polluted water. Herein, an electrocatalyst prepared by a simple method that embedded Co into ZIF-8 and then calcined to form a nitrogen-doped graphitic carbon structure was prepared. The prepared Co–NC composite retained the original morphology of ZIF-8 while effectively immobilizing metallic Co within the graphite carbon layers, providing more metallic active sites, which contributed to the exceptional performance of the Co–NC composite in electrocatalytic nitrate reduction reaction (NO₃RR), achieving the highest faradaic efficiency (FE) at a relatively low overpotential, which achieved an NH₃ yield of up to 1.96 mg h⁻¹ cm⁻² and a FE of 35.01% at −0.5 V (vs. RHE), with excellent electrochemical stability and reproducibility under ambient conditions. The high porosity and superior conductivity of the Co–NC material enabled efficient electrocatalytic reduction of NO₃⁻ to synthesize NH₃. This study underscored the promising prospects of MOF-derived materials in electrochemical NO₃⁻ reduction and paved the way for future developments.