Interface engineering of UiO-66-derived ZrO2@TiO2/Ag(AgCl) multiphase heterostructure for enhanced UV-driven photocatalytic degradation and disinfection.

Efficient separation and transport of photogenerated charge carriers remain key challenges in wide-bandgap semiconductor photocatalysts. Herein, a UiO-66-derived ZrO2@TiO2/Ag(AgCl) multiphase composite was fabricated through a solvothermal-calcination route and evaluated for UV-driven dye degradation and photo-disinfection. X-ray diffraction, electron microscopy, Fourier-transform infrared spectroscopy, and UV-visible diffuse reflectance spectroscopy verified the coexistence and intimate interfacial coupling of ZrO2, TiO2, Ag, and AgCl domains. The composite exhibited an apparent optical bandgap of 4.24 eV and enhanced UV-responsive photocatalytic activity. Relative to the reference samples, the optimized composite showed a lower charge-transfer resistance (10.85 Ω), quenched photoluminescence emission, and an approximately 1.9-fold higher transient photocurrent response, supporting improved overall photoinduced carrier transport and extraction. The measured component band-edge potentials provide a thermodynamic framework for a proposed Ag-mediated interfacial charge-transfer model, while the photoelectrochemical behavior and reactive-species trapping results support improved carrier dynamics and the participation of reactive oxygen species. Within this proposed model, Ag-containing interfaces are hypothesized to facilitate selective interfacial recombination, thereby preserving charge carriers with strong redox capability. However, the present measurements do not directly resolve the phase-specific locations or migration directions of photogenerated carriers. Because the trapping experiments were conducted in the presence of H2O2, which can act as an electron acceptor and contribute to additional reactive-oxygen-species-generating pathways, the individual origins of •OH and •O2- cannot be uniquely assigned. Under the tested UV-irradiation conditions, the optimized composite achieved 97.8% methylene blue degradation within 4 h in the presence of 1.75% H2O2, exhibited activity toward methyl orange, rhodamine B, and rhodamine 6G, and showed photoinduced antibacterial activity against Escherichia coli and Staphylococcus aureus at 5 mg mL- 1. The photocatalyst maintained a degradation efficiency of 83.98% after five consecutive cycles. These results demonstrate the potential of UiO-66-derived multiphase heterostructures as multifunctional UV-driven photocatalysts for dye degradation and photo-disinfection.