Work

Synergetic Relay Between Atomic Hydrogen and Chlorine Radicals Enables Efficient Nitrate‐to‐Nitrogen Gas Conversion

Year: 2025

Type: article

Abstract: ABSTRACT The excessive discharge of nitrate (NO 3 − ) contamination in wastewater can lead to eutrophication of aquatic ecosystems, calling for technologies that can selectively reduce it to non‐toxic and harmless nitrogen gas (N 2 ) reducing the secondary pollution risks. This work, for the first time, reports a synergic reduction−oxidation process that achieves highly efficient conversion of NO 3 − to N 2 via a relay strategy using reactive atomic hydrogen (H*) and chlorine radicals (Cl•). The photoelectrocatalytic system comprising a CuO‐Fe 3 O 4 /nickel foam (CuO‐Fe 3 O 4 /NF) and TiO 2 nanotube arrays as the cathode and photocathodes, respectively, achieving a NO 3 − removal rate of 97.4% and N 2 selectivity close to 100%, while significantly suppressing the key bridging intermediate NH 4 + accumulation and outperforming most reported values up to date. Mechanistic studies reveal that the cathodic CuO‐Fe 3 O 4 component achieves the strong adsorption ability at CuO sites and hydrogenation reaction at Fe 3 O 4 sites for activating H 2 O to generate reductive atomic H*, then highly selectively generate the NH 4 + by spatial decoupling adsorption‐transformation processes. Subsequently, in‐situ generated Cl• by the photoanode TiO 2 , effectively scavenges and oxidizes NH 4 + , ultimately converting it to N 2 via the tandem radical‐mediated reactions. Our discovery provides a sustainable strategy and drive great advances for removing nitrate pollutants in real aquatic environments.

Source: Advanced Science

DOI: 10.1002/advs.202522147