Preparation and properties of visible light responsive ZrTiO 4/Bi 2O 3 photocatalysts for 4-chlorophenol decomposition

Abstract

In this work, visible light responsive (VLR) ZrTiO 4/Bi 2O 3 photocatalysts were successfully synthesized by a hydrothermal method. The prepared ZrTiO 4/Bi 2O 3 photocatalysts were characterized by X-ray diffraction studies (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and transmission electron microscopy (TEM) analyses. DRS results revealed that the extent of light absorption towards the visible region of the spectrum increased with an increase in the calcination temperature of the catalysts up to 450 °C and then started to decrease. The decrease in absorption at high temperatures was mainly due to the formation of polycrystalline ZrTiO 4/Bi 2O 3 from the tetragonal Bi 2O 3 pure oxide particles. All the metals present in the ZrTiO 4/Bi 2O 3 composite nano-particles also exhibited corresponding oxide states. Particle sizes of about 7 nm were obtained during this combined method of preparation, especially with the catalysts calcined at 450 °C. The photocatalytic activity of the catalysts was measured using 4-chlorophenol as a model pollutant for these environmental remediation studies. Among the catalysts calcined at different temperatures, the samples calcined at 450 °C showed the most remarkable degradation of 4-chlorophenol, higher than not only the other calcined catalysts but also the commercially available Degussa P-25. This is due to the formation of smaller particle sizes, a higher surface area and stronger absorption in the visible light irradiation for these catalysts calcined at 450 °C. Thus, such new VLR photocatalysts can be expected to work effectively under visible light regions as an applicable alternative photocatalyst for commercial scale use.