On the assessment of photocatalytic activity and charge carrier mechanism of TiO₂@SnO₂ core-shell nanoparticles for water decontamination

We synthesize TiO2@SnO2 core-shell nanoparticles (NPs) by a facile two-step aqueous sol-gel method and their photocatalytic activity is compared with the pure TiO2 and SnO2 NPs for degradation of methylene blue under UV irradiation. The chemical property, crystal structure and morphology of the synthesized samples are studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM) and transmission electron microscope (TEM) techniques. The mechanisms of electron–hole recombination and separation of charge carriers are studied by photoluminescence (PL) and diffuse reflectance spectroscopy (DRS). Furthermore, the kinetics study of photocatalytic degradation of dye methylene blue is carried out based on Langmuir-Hinshelwood model. The remarkable enhancement in photocatalytic activity of the core-shell nanoparticle compared to its constituents is attributed to the lower recombination rate of charge carriers in the core-shell heterostructure.