In situ ammonia synthesis and energy generation via aqueous Zn–NO3− batteries

Abstract

The sustainable generation of electricity and ammonia (NH₃) is essential for modern industrial advancement. The electrochemical nitrate reduction reaction (NO₃RR) provides a sustainable pathway for NH₃ production, complemented by pollution mitigation. Nevertheless, this process is constrained by limited nitrate adsorption, multiple competing reactions, and sluggish kinetics involving coupled proton–electron transfer steps, thereby reducing NH₃ selectivity. Herein, we have utilised FeCu(1:2)S_x as a cathode catalyst in Zn–NO₃⁻ battery to produce NH₃ via the NO₃RR, simultaneously generating electricity. The assembled Zn–NO₃⁻ battery demonstrated a remarkable faradaic efficiency (F.E.) of 98.96% for NH₃ and a power density of 5.2 mW cm⁻². Real time NH₃ production examined by in situ electrochemical Raman and attenuated total reflectance-Fourier transform infrared (ATR FT-IR) spectroscopy revealed that Cu promotes NO₃⁻ adsorption and reduction to NO₂⁻, while Fe facilitates hydrogenation resulting in an NH₃ yield of 3.69 mg h⁻¹ cm⁻² at −0.9 V vs. RHE. As a proof of concept, two Zn–NO₃⁻ batteries connected in series powered 62 LEDs for over 70 h.