Oxygen doping enables tailored built-in electric fields in FeOCl/g-C₃N₄ heterojunctions for enhanced peroxymonosulfate activation

Abstract

Regulating metal-support interactions enables rational design of catalysts with enhanced performance in Fenton-like oxidation reactions. Here, a novel oxygen-doped, stalactite-like g-C3N4 supported FeOCl (FeOCl-OCN) is successfully synthesized. Due to the modulation of O doping to the work function (Φ) of g-C3N4 support, a delicate built-in electric field (BIEF) oriented from OCN to FeOCl is constructed. Driven by large work function difference (ΔΦ = 3.235 eV), the interfacial charge transfer manipulates electron redistribution to achieve a rearrangement of structural Fe(II)/Fe(III). Based on theoretical calculations and mechanism insight, the interaction between FeOCl and OCN exhibits a stronger binding ability to peroxymonosulfate (PMS) and reduces the energy barriers for *O formation, therefore favoring a higher yield of singlet oxygen (1O2) and high-valent iron-oxo (Fe(IV)═O)− species. As a result, the FeOCl-OCN/PMS system demonstrates a nonradical-dominated pathway, delivering high activity (k obs = 0.250 min−1), robust tolerance to pH variation and resistance, and excellent stability.