An electrocatalyst prepared via a metal–polyphenol assembly strategy for efficient nitrate reduction

Abstract

The electrocatalytic nitrate reduction reaction (NO₃RR) is promising for achieving the dual goals of sustainable ammonia production and wastewater remediation. Nevertheless, the highly selective ammonia (NH₃) synthesis remains a formidable challenge, primarily attributed to the complex reaction pathway, instability of metal-based catalysts, and the competitive hydrogen evolution reaction (HER). Herein, we propose a novel electrocatalyst (TA–Fe/Co₃O₄) prepared via a metal–polyphenol assembly strategy integrating natural plant polyphenol (tannic acid, TA) and iron (Fe) molecular assembly. Active components are anchored and stably dispersed on TA, while Fe incorporation is conducive to accelerating reaction kinetics, synergistically enhancing the electrocatalytic efficiency of spinel Co₃O₄. The catalyst delivers a faradaic efficiency (FE) of up to 94.36% at −0.2 V vs. RHE and an exceptional NH₃ yield rate of 206.50 μmol h⁻¹ cm⁻² (−0.5 V vs. RHE). This work presents a facile and economical route for designing efficient transition metal oxide catalysts for the reduction of nitrate to NH₃.