The effect of PEDOT morphology on hexavalent chromium reduction over 2D TiO2/PEDOT photocatalyst under UV–vis light

The present study represents an approach to apply organic-inorganic hybrid materials for photocatalytic removal of heavy metals from the aqueous environment. The photocatalytic activity of the semiconductor modified with the conjugated polymer may depends on the conjugated polymer type, its amount and morphology. Therefore, in the present study the effect of poly (3, 4-ethylenedioxythiophene) (PEDOT) morphology on adsorption and photoreduction of Cr(VI) to Cr(III) under simulated solar light (UV–vis) and vis light (λ > 400 nm) was investigated. The composite of titanium (IV) oxide and PEDOT of different morphology was obtained using the water-in-oil microemulsion method. The obtained hybrid photocatalysts were characterized by diffuse reflectance spectroscopy (DR/UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), specific surface area (BET) and X-ray photoelectron spectroscopy (XPS) analyzes. PEDOT and its composites with TiO2 nanosheets of anatase were used for the degradation of highly toxic Cr(VI) under the simulated solar light. The 2D TiO2/PEDOT composite with PEDOT microvesicular morphology reveals the highest efficiency of Cr(VI) photoreduction to Cr(III). The synergistic effect of 2D TiO2 and PEDOT for Cr(VI) removal is observed in UV–vis light, resulting from the increased separation of photogenerated electrons and holes involved in redox reactions. Furthermore, the 2D TiO2/PEDOT composite with PEDOT microvesicular morphology reveals improved photocatalytic activity under visible light irradiation (λ > 400 nm).