Facile one-pot synthesis of tungsten oxide (WO3-x) nanoparticles using sub and supercritical fluids

Abstract

Tungsten oxide (WO3) and tungsten blue oxide (WO3-x) were synthesized using sub and supercritical water and methanol. Crystalline tungsten oxides were formed with subcritical water at 250 degrees C, which shows lower production temperature compared to conventional solid-state methods. Glycerol hydro thermal reduction and supercritical methanol were both found to be effective in obtaining crystalline tungsten blue oxides and this is a great advantage since hydrogen is not required in the process. The synthesized particles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and near edge X-ray absorption fine structure (NEXAFS). NEXAFS results showed that sub and supercritical methanol was more effective in reduction of tungsten oxides compared to glycerol hydrothermal reduction. (C) 2016 Elsevier B.V. All rights reserved.