Boosting tetracycline degradation via synergistic photo-self-Fenton/peroxymonosulfate activation using sea-urchin-like iron-doped nickel phosphonate catalysts

Background Transition metal phosphonates have demonstrated significant potential in catalysis due to their versatile coordination configurations and tunable structural frameworks. However, their direct application in photo-self-Fenton and peroxymonosulfate activation systems for organic pollutant degradation has rarely been explored. Methods In this study, a novel three-dimensional (3D) sea-urchin-like iron-doped nickel phosphonate (NiFeP2) was synthesized and employed as a catalyst in a photo-self-Fenton system for the efficient degradation of tetracycline (TC). Characterization revealed that the hierarchical architecture of NiFeP2 not only enhances light absorption and exposes abundant active sites but also facilitates synergistic peroxymonosulfate activation and photo-self-Fenton reactions, thereby improving catalytic performance. Significant findings Under optimized conditions, NiFeP2 achieved an apparent reaction rate constant (k obs ) of 0.0589 min⁻¹ for TC degradation, demonstrating superior pollutant removal efficiency. The synthesized NiFeP2 photocatalyst exhibited excellent recyclability and maintained stable photocatalytic performance over multiple cycles, demonstrating its promising suitability for real-world wastewater purification applications. This work presents an effective photo-self-Fenton system based on NiFeP2, offering a promising strategy for the remediation of refractory organic pollutants in wastewater treatment.