Facile synthesized Cu2O nanoparticles for high NO3RR yield in ultralow nitrate concentration

Abstract

The electrochemical reduction of nitrate (NO3-) to ammonia (NH3) presents a sustainable strategy for wastewater treatment and NH3 production. However, achieving high NH3 yields at low NO3- concentration often involves a trade-off, posing a significant challenge to the catalyst performance. In this study, Cu₂O nanoparticles (NPs) electrocatalysts were prepared via a simple in situ reduction method for the electrocatalytic reduction of NO3- to NH3 (NO3RR). When simulating NO3RR in an industrially polluted, high-concentration electrolyte containing 100 mM NaNO3, the catalyst achieved FENH3 of 95.74% at -0.8 V vs.SHE and NH₃ yield of 24.01±0.52 mgNH3·mgcat⁻¹·h⁻¹ at -0.9 V vs.SHE, representing a leading performance level. Delightfully, the Cu₂O NPs electrocatalyst achieved a Faradaic efficiency of 58.82 ± 1.53% for NH3 production, with a partial current density of 25.02 mA·cm-2 at -0.8 V vs. SHE in an ultralow electrolyte (1 mM NaNO3). The NH₃ yield reached 5.66 ± 0.18 mgNH3·mgcat⁻¹·h⁻¹ at -0.9 V vs. SHE, demonstrating remarkable performance under ultra-low NO₃⁻ concentration conditions. Additionally, in-situ Fourier infrared (FTIR) was employed to analyze key reaction intermediates and elucidate the reaction mechanism. This study provides a facile and practical approach for achieving high NH3 yields, even at ultralow NO3- concentration.