Efficient Photocatalytic Activation of Peroxymonosulfate by T-Derivative Carbon Dots/TiO ₂ Composites: Achieving Complete Tetracycline Degradation and Dual Fluorescent Labeling Function

Using chlorinated T-Red as a precursor, chlorine-doped, orange-emissive carbon dots (T-CDs) were synthesized via a one-step hydrothermal method, achieving a high quantum yield of 48.5%. When 150 μL of T-CDs was immobilized on TiO₂, the resulting composite material completely degraded 20 mg L⁻¹ of tetracycline within 30 min under UV/peroxymonosulfate (UV/PMS) conditions and retained over 98% of its catalytic activity after five successive cycles. Electron paramagnetic resonance (EPR) and radical scavenging experiments confirmed that singlet oxygen (¹O₂) was the dominant reactive species driving the oxidation process. Beyond environmental remediation, the T-CDs were also capable of penetrating plant petals and exhibited bright orange fluorescence under 365 nm UV illumination, highlighting their dual functionality in antibiotic degradation and sustainable plant fluorescence decoration.