Photoelectrocatalytic reduction of nitrate to nitrogen gas by Cu2O nanorod arrays on Cu foams with high stability

Abstract

Selective reduction of nitrate to nitrogen gas is a great potential strategy for removing nitrogen element from nitrate-contaminated water bodies. Herein, highly efficient and selective reduction of nitrate to nitrogen gas has been demonstrated with a Cu₂O nanorod array based on photoelectrochemical catalysis. The p-type semiconductor Cu₂O nanorod array, engineered with a high specific surface area and abundant active sites, enables significant reduction of nitrate under light illumination. Crucially, external light irradiation lowers the electrical bias required for electrocatalytic NO₃⁻ reduction, simultaneously improving catalytic efficiency and long-term stability by suppressing the reduction of Cu₂O to metallic Cu. Remarkably, N₂ selectivity of up to 90% and 76% was achieved across a wide pH range (acidic, neutral, and alkaline conditions) and in real nitrate-containing lake water. This study establishes a novel and practical approach for sustainable nitrate remediation in diverse aqueous systems with potential applications in wastewater treatment and environmental remediation.