Enhanced photocatalytic activity of CdWO4/BaTiO3 heterostructure for dye degradation

Abstract

The novel UV active photocatalysts of (1 − x)CdWO₄–xBaTiO₃ (where x = 10, 30, 50 and 70 wt%) heterostructures were synthesized using the hydrothermal technique. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR) spectroscopy, and photoluminescence (PL) techniques. The photocatalytic activities of BaTiO₃, CdWO₄ along with all CdWO₄/BaTiO₃ heterostructures were evaluated for the degradation of methylene blue (MB) dye in an aqueous solution under UV irradiation and it was found that the CdWO₄/BaTiO₃ (70 : 30 wt%) heterostructure exhibited the highest photocatalytic activity within 45 minutes compared to BaTiO₃ and CdWO₄. The scavenger tests confirmed that OH˙, O₂˙⁻ and h⁺ radicals were the main species for the MB degradation. The calculated redox potentials of both BaTiO₃, CdWO₄ semiconductors indicated that the charge transfer between these two is responsible for the enhanced photocatalytic activity of CdWO₄/BaTiO₃ heterostructures. Accordingly, the possible mechanisms of the separation of photo-induced electron–hole pairs and charge transfer and also the generation of radicals for MB degradation under UV irradiation were proposed in detail. Our findings clearly suggest that the integration of ferroelectric BaTiO₃ with semiconducting CdWO₄ could be an effective way to expedite MB dye degradation.