Co-grown novel S-scheme tubular P-UCN/S-TCN homojunction mediates photocatalysis-PMS activation synergistic system for efficient degradation of antibiotic.

The low photogenerated carrier separation and transport ability of the photocatalyst are the main factors inhibiting the photocatalytic activity. The construction of composite photocatalysts can effectively improve the efficiency of photogenerated carriers. However, the problem of reduced photocatalyst stability and catalytic activity due to easy separation of unstable composite interfaces has not been well solved for a long time. Therefore, in this work, a co-growth strategy was put forward to thermally co-polymerize sulfur-containing tubular supramolecular precursors with urea in order to achieve the growth of porous g-C₃N₄ nanoparticles (P-UCN) on the sulfur-doped tubular g-C₃N₄ (S-TCN), thus to successfully prepare P-UCN/S-TCN homojunction photocatalysts with chemically bonded stable composite interfaces. Furthermore, a coupled photocatalytic-peroxymonosulfate (PMS) activation system was constructed to further promote the photogenerated carrier separation of P-UCN/S-TCN as well as the catalytic activity of the reaction system through the electron donor-acceptor relationship between P-UCN/S-TCN and PMS. Experimental characterization and DFT theoretical calculations together revealed the band gap structural characteristics and the direction of electron flow of the P-UCN/S-TCN S-scheme homojunction, and confirmed the successful construction of a stable chemically bonded homojunction interface. Then the results of catalytic activity test of P-UCN₁/S-TCN₁ showed a high tetracycline hydrochloride (TCH) degradation efficiency (93.5%) within 30 min, and also demonstrated 100% degradation efficiency for Rhodamine B (RhB). This work made important progress in the design of a novel stable S-scheme homojunction interface and provided a reference for the application of photocatalysis-PMS coupling system in environmental remediation.