Construction of Ru-anchored tubular carbon nitride for boosted photocatalytic degradation of norfloxacin: Unravelling synergistic mechanism of nitrogen defect engineering and photo-Fenton like reaction

Abstract

Engineering the interfacial active sites of metal-anchored photocatalyst is vital for advancing the photo-Fenton-like reactions. Herein, a novel tubular gC₃N₄ (TgCN) with a well-defined 1D morphology was constructed using simple, template-free hydrothermal strategy. Ru atoms were subsequently anchored onto TgCN, exploiting the high affinity of RuN coordination to achieve uniform dispersion, prevent agglomeration, and maximize the exposure of active sites for H₂O₂ activation. Comprehensive characterization confirmed the successful formation of the tubular structure with strong RuN coordination, which led to enhanced light absorption, improved charge separation and a higher surface area. The resulting Ru/TgCN-3 SACs displayed outstanding photo-Fenton catalytic activity towards a pharmaceutical pollutant, achieving 99.9% norfloxacin (NFX) degradation in water with k = 0.0076 min⁻¹ across a wide pH range (pH 3–11). Radical trapping experiments identified •OH and O₂^•- as dominant reactive species, while the multiple oxidation states of Ru were proposed to accelerate the Fenton-like reaction. The Ru/TgCN-3 SACs exhibit robust stability over six consecutive cycles and maintaining high degradation efficiency in real wastewater, underscoring its promise for practical applications. Gas chromatography-mass spectrometry analysis revealed two major degradation pathways for NFX, while ecotoxicology assessment of transformation products confirmed the environmental relevance and safety of the approach. This study elucidates the synergistic mechanism between nitrogen-defect engineering in the TgCN support and RuN coordination for boosting H₂O₂ activation, providing a strategy for designing high performance photo-Fenton catalyst for efficient water remediation.