Visible-Light-Assisted Photocatalytic Degradation of Phenolic Compounds Using Bi2S3/Bi2W2O9 Heterostructure Materials as Photocatalyst

In this work, bismuth sulphide (Bi2S3)/bismuth tungstate (Bi2W2O9) heterostructure materials were prepared and studied as photocatalyst for decomposition of phenolic compounds under visible light. The Bi2S3 nanomaterial was deposited over the combustion synthesized Bi2W2O9 material using a hydrothermal procedure. The heterostructures were characterized using X-ray diffraction (XRD), photoluminescence (PL), photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The presence of crystalline orthorhombic Bi2S3 and Bi2W2O9 phases was confirmed from XRD analysis. Morphologically, the heterostructure materials contained Bi2S3 nano-rods grown uniformly over Bi2W2O9 micron size plates. The heterostructure materials displayed improved absorption features in visible region and enhanced separation of excitons. The Bi2S3/Bi2W2O9 materials displayed excellent photocatalytic activity towards the degradation of phenolic compounds from aqueous sources. Structurally diverse phenol moieties could be mineralized effectively with high efficiency (> 80%) within 2 h. The hydroxyl and superoxide radicals were identified as reactive species for phenol degradation, the formation of which was confirmed from spectroscopic analysis. The mechanism of photocatalytic degradation of phenol over the Bi2S3/Bi2W2O9 photocatalyst surface was also described.