title: Facile and controlled synthesis of aligned WO3nanorods and nanosheets as an efficient photocatalyst material.
abstract: In this work, we have performed a facile and controlled synthesis of WO3nanorods and sheets in different crystal phases (triclinic, orthorhombic and monoclinic) of WO3using the sol-gel method. The detailed structures of the synthesized materials were examined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy measurements. The shapes and crystal phases of the WO3nanostructures were found to be highly dependent on the calcination temperature. The variation in crystalline phases and shapes is modified the electronic structure of the samples, which causes a variation in the value of optical band gap. The value of the Raman line intensity ratio I264/I320has been successfully used to identify the structural transition from the triclinic to the orthorhombic phase of WO3. The PL spectra of the synthesized products excited at wavelengths 380, 400, and 420nm exhibit intense emission peaks that cover the complete visible range (blue-green-red). The emission peaks at ~460 and ~486nm were caused by the near band-edge and band to band transition, respectively. The peaks in spectral range 500-600nm might be originated from the presence of oxygen vacancies lying within the energy band gap. The synthesized WO3nanostructures showed improved photocatalytic activity for the photodegradation of MB dye. The enhanced photocatalytic activity of WO3nanosheets compared to WO3nanorods for photodegradation of methylene blue (MB) dye could be due to the shape of the nanostructured WO3. The sheet type of structure provides more active surface for the interaction of dye molecules compared to the rods, which results in a more efficient degradation of the dye molecules.
authors.affiliation: Department of Physics, Motilal Nehru National Institute of Technology Allahabad, 211004, India.
authors.forename: Bilal
authors.initials: B
authors.lastname: Ahmed
authors.affiliation: Department of Physics, Motilal Nehru National Institute of Technology Allahabad, 211004, India.
authors.forename: Sumeet
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Physics, Motilal Nehru National Institute of Technology Allahabad, 211004, India; Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany. Electronic address: animesh@mnnit.ac.in.
authors.forename: Animesh K
authors.initials: AK
authors.lastname: Ojha
authors.affiliation: Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Donfack
authors.affiliation: Department of Physics and Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Materny
keywords: Nanorods/nanosheets; Optical materials/properties; Photocatalysis; Tungsten compounds