Hollow Spherical Hierarchical MoO3/SiO2–TiO2 Structures for Photocatalytic Decomposition of Organic Pollutant in Water

• Spherical MoO 3 /TiO 2 –SiO 2 composites with core/shell type, where the core is an α-MoO 3 sphere and the shell is TiO 2 anatase with SiO 2 amorphous was synthesized. • Hierarchical structures in which layer are linked through oxygen (Ti-O-Mo and Si-O-Mo) results in lower oxygen vacancy concentrations in MoO 3 (0.0425) and a reduced bandgap width (2.58 eV). • The MoO 3 /TiO 2 –SiO 2 composites exhibit high photocatalytic activity (rate constant is 0.0645 min ‒1 ). • The MoO 3 /TiO 2 –SiO 2 layered spherical composites is a promising candidate material for photocatalytic decomposition of organic dyes in textile waste water. In this study MoO 3 /TiO 2 –SiO 2 layered spherical composites, having hierarchical structure, were synthesized on TOKEM-320Y anion exchanger template using by sol-gel methods. Properties of MoO 3 /TiO 2 –SiO 2 composites were characterized by XRD, EDS, SEM, 3D X-ray microtomography, Raman, IR, DRS, BET, and PL techniques. The SEM, 3D X-ray microtomography and EDS analysis showed hollow spherical composites with diameters ranging from 200 to 400 μm with core/shell structure. The formation of TiO 2 –SiO 2 shell on the MoO 3 core results in lower oxygen vacancy concentrations in composite (0.0425) and a reduced bandgap width (2.56 eV in compare to 3.19 eV for MoO 3 sample, which was analyzed through the UV–VIS DRS method). The performance of MoO 3 /TiO 2 –SiO 2 composites was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution irradiated with an I 2 excilamp (λ max = 312 nm). The photoabsorption energy properties of MoO 3 /TiO 2 –SiO 2 composites are related to the interaction between TiO 2 –SiO 2 and MoO 3 which occurs through oxygen in Ti-O-Mo and Si-O-Mo. The MoO 3 /TiO 2 –SiO 2 composites exhibited a much higher photocatalytic activity (rate constant is 0.0645 min ‒1 , degradation efficiency is 93% (20 min). This work demonstrates the relation between the formation of heterostructure in core/shell composite and its photocatalitic activity, providing fundamental guidance to improve photocatalytic performance of materials.