Tuning the electronic structure of Fe2O3 via sulfur doping to boost peroxymonosulfate activation for high-efficiency glyphosate degradation

The introduction of sulfur endows Fe 2 O 3 with superior catalytic activity. • Sulfur doping regulates Fe spin state to accelerate interfacial electron transfer. • The formation of Fe S bonds triggers abundant oxygen vacancies. • The S-Fe 2 O 3 /PMS system achieves efficient glyphosate degradation dominated by 1 O 2 . Glyphosate residues in aquatic ecosystems pose serious threats to ecological safety and public health owing to their strong biological recalcitrance and intrinsic toxic properties. Herein, sulfur-doped Fe 2 O 3 (designated S-Fe 2 O 3 ) is synthesized via a facile sulfur annealing strategy to tune the electronic configuration of Fe sites and enhance its catalytic activity toward peroxymonosulfate (PMS) activation. Comprehensive characterizations confirm the successful formation of Fe S bonds, abundant oxygen vacancies, and an increased fraction of surface Fe 2+ after sulfur modification. More importantly, sulfur incorporation regulates the spin state of Fe active sites and lowers the work function of Fe 2 O 3 , which accelerates interfacial charge transfer. In addition, the generated Fe S bonds shift the Fe d-band center upward, further elevating the PMS activation capability of S-Fe 2 O 3 . Benefiting from the optimized electronic structure, the S-Fe 2 O 3 /PMS system realizes 94.6% glyphosate elimination within 14 min, with its reaction rate constant 7.8 times larger than that of bare Fe 2 O 3 . Meanwhile, S-Fe 2 O 3 exhibits excellent pH adaptability and prominent anti-interference performance against coexisting inorganic anions. Radical trapping and EPR tests further validate that 1 O 2 serves as the major contributor for glyphosate degradation, while both SO 4 •– and •OH also contribute to pollutant removal. Collectively, this work offers a facile modification route for iron-based catalysts and provides a promising strategy for remediating glyphosate-contaminated wastewater. Download: Download high-res image (252KB) Download: Download full-size image