Single step synthesis of WO3 nanoparticles by wire explosion process and its photocatalytic behaviour

Tungsten (W) wires are exploded in oxygen ambience to get tungsten oxide (WO3) nanoparticles (NPs). Energy stored in the capacitors (EC) is used to overcome the sublimation energy of wire. Energy ratio (K, ratio of EC and sublimation energy) and oxygen pressure (P) are two control parameters for the particle phase and morphology in the wire explosion process. X-ray diffraction (XRD) patterns confirmed the partial oxidation of W for low values of K. For K = 2, oxidation increases with increase in P. For K = 10, complete oxidation was achieved irrespective of P. Particles are spherical in shape as observed from scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs. Particle size follows a log-normal distribution with a least mean size of 24.1 nm. UV-vis diffuse reflectance spectroscopy (DRS) was used to measure the absorbance of NPs (complete WO3 with least mean size) for band gap measurement. The band gap was found to be 2.92 eV (visible region). NPs are used as photocatalyst to degrade aqueous solution of methylene blue (MB) under visible light irradiation. 500 mg l−1 of WO3 NPs were optimum to degrade 10 mg l−1 MB in 120 min.