Optimization of TiO₂/ZSM-5 photocatalysts: Energy band engineering by solid state diffusion method with calcination

In this work, based on a type of energy band engineering strategy as calcination, TiO2/ZSM-5 hybrids for photodegradation of methyl orange (MO) in water under UV light have been developed via a facile solid state diffusion method. Effects of varied calcination temperatures on TiO2/ZSM-5 hybrids have been systematically characterized including XRD, FT-IR, SEM, TEM, EDX mapping, BET, PL, EIS, UV-vis DRS, active species trapping experiments and Mott-Schottky curves. It was found that the calcination temperature influenced photocatalytic activity, typically on physicochemical properties of materials and adjustment for the energy gap and band position of TiO2. The XRD analysis revealed that hybridization of ZSM-5 kept the crystal phase of TiO2 as anatase unchanged with the high-rising calcined temperature. The optimum sample calcined at 450 °C named as Z-T (450) presented nearly 99% degradation rate for MO, owing to optimal uniform distribution, highest specific surface area and best charge separation/transfer efficiency. The FT-IR comparison result that the functional groups and peak strength of the used catalyst were alike as before, showed the stability of photocatalyst. Adoption of calcination strategy does provide not only a clean, low-cost and highly efficient path to approach the complete degradation of azo dyes, but also a chance for photocatalytic technology to fulfill the implementation in industrial applications.