Ti-O-Zn Interfacial Bonding in TiO2-ZIF-8 Heterojunctions for Enhanced Photocatalytic Dye Degradation

TiO 2 is a widely studied photocatalyst, but its practical performance is limited by poor light utilization and rapid recombination of photogenerated charge carriers. Herein, a TiO 2 -ZIF-8 heterojunction with a chemically bonded interface was constructed through the formation of Ti-O-Zn interfacial bonds. This design integrates the strong adsorption capacity of ZIF-8 with improved charge separation and transfer across the heterojunction. The optimized TiO 2 -ZIF-8 composite showed markedly enhanced photocatalytic activity, achieving 94.6% degradation of methylene blue within 120   min under simulated solar irradiation. Its apparent rate constant reached k = 0.01508   min -1 , which is 1.55 and 2.38 times higher than those of pristine TiO 2 and ZIF-8, respectively. XPS, FTIR, TEM, and PL results confirm the successful construction of the heterojunction and reveal the key role of Ti-O-Zn bonding in strengthening interfacial interaction and facilitating photogenerated carrier migration. Meanwhile, the strong interfacial interaction improved the structural stability of the composite and helped inhibit nanoparticle agglomeration during photocatalysis. Overall, this work provides new insight into the design of high-performance MOF-based photocatalytic systems through interfacial chemical bond engineering.