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

In this study MoO3/TiO2-SiO2 layered spherical composites, having hierarchical structure, were synthesized on TOKEM-320Y anion exchanger template using by sol -gel methods. Properties of MoO3/TiO2-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 mu m with core/shell structure. The formation of TiO2-SiO2 shell on the MoO3 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 MoO3 sample, which was analyzed through the UV-VIS DRS method). The performance of MoO3/TiO2-SiO2 composites was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution irradiated with an I2 excilamp (lambda max = 312 nm). The photoabsorption energy properties of MoO3/TiO2-SiO2 composites are related to the interaction between TiO2-SiO2 and Mo-O3 which occurs through oxygen in Ti-O-Mo and Si-O-Mo. The Mo-O3/ TiO2-SiO2 composites exhibited a much higher photocatalytic activity (rate constant is 0.0645 min-1, degradation efficiency is 93% (20 min). This work demon-strates the relation between the formation of heterostructure in core/shell composite and its photocatalitic activity, providing fundamental guidance to improve photocatalytic performance of materials.

Automated summary

Hierarchical MoO3/TiO2-SiO2 layered spherical composites were synthesized on anion exchanger template, and their properties and photocatalytic performance were characterized. The formation of TiO2-SiO2 shell on the MoO3 core led to lower oxygen vacancy concentrations and reduced bandgap width. The MoO3/TiO2-SiO2 composites showed higher photocatalytic activity.