In situ self-assembly green synthesis of P-doped tubular carbon nitride for photocatalytic activation of PMS to rapidly degrade organic pollutants.

Peroxymonosulfate (PMS)-assisted visible-light photocatalytic degradation of organic pollutants using graphitic carbon nitride (g-C₃N₄) presents a promising and environmentally friendly approach. However, pristine g-C₃N₄ suffers from limited visible-light absorption and low charge-carrier mobility. In this study, a phosphorus-doped tubular carbon nitride (5P-TCN) was synthesized via a precursor self-assembly method using phosphoric acid and melamine as raw materials, eliminating the need for organic solvents or templates. The 5P-TCN catalyst demonstrated enhanced visible-light absorption, improved charge transfer capability, and a 5.25-fold increase in specific surface area (31.092 m²/g), which provided abundant active sites to efficiently drive the PMS-assisted photocatalytic reaction. The 5P-TCN/vis/PMS system exhibited exceptional degradation performance for organic pollutants across a broad pH range (3-9), achieving over 92 % degradation of Rhodamine B (RhB) within 15 min. Notably, the system retained > 98 % RhB degradation efficiency after three consecutive operational cycles, demonstrating robust operational stability and reusability. Moreover, key parameters influencing, active radicals, degradation pathways, and potential mechanisms for RhB degradation were systematically investigated. This work proposes a green and cost-effective strategy for developing high-efficiency photocatalysts, while demonstrating the exceptional capability of a PMS-assisted photocatalytic system for rapid degradation of RhB.