Synthesis of three-dimensional WO₃ octahedra: Characterization, optical and efficient photocatalytic properties

Three dimensional (3D) novel tungsten trioxide (WO₃) octahedra have been prepared by a simple surfactant/catalyst-free hydrothermal method. The phase and morphological structure of the as-synthesized material were analysed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). FESEM results showed that the as-prepared WO₃ octahedron structure was in the range of 1-5 μm. Furthermore, the optical properties like the UV-VIS absorption spectrum, photoluminescence (PL) spectrum and Fourier transform infrared (FTIR) spectra of the product were also studied. The {120} side facet of the exposed surface of the resulting product with a large surface area (15.26 m² g^-1), effective crystallinity and increased number of surface active sites exhibited excellent photocatalytic efficiency with a higher rate constant (0.03254 min^-1) for the degradation of methylene blue (MB) under visible light irradiation. The photocatalytic performance of as-synthesized WO₃ octahedra was about 5.33 times greater than that of the bulk sample. The apparent excellent photocatalytic efficiency of the prepared sample can be attributed to large surface area and a highly reactive {120} facet of the exposed surface of the WO₃ octahedra.