Synthesis of hexagonal WO₃nanowires by microwave-assisted hydrothermal method and their electrocatalytic activities for hydrogen evolution reaction

Abstract

Hexagonal WO 3 (hex-WO 3 ) nanowires with high aspect ratio and crystallinity have been prepared for the first time by a microwave-assisted hydrothermal method. By using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy, the phase and morphology of the products were identified, which were controlled by reaction temperature, holding time and added salts. Uniform hex-WO 3 nanowires with a diameter of 5-10 nm and lengths of up to several micrometres were synthesized by a microwave-assisted hydrothermal process at 150 C for 3 h in a solution containing (NH 4 ) 2 SO 4 as a capping reagent and Na 2 WO 4 as a starting material. The aspect ratio and specific surface area of hex-WO 3 nanowires were 625 and 139 m 2 g À1 , respectively, which represented one of the highest values reported for WO 3 . The electrocatalytic activity for hydrogen evolution reaction of hex-WO 3 nanowires was also investigated by cyclic voltammetry and linear sweep voltammetry. The results demonstrated that hex-WO 3 nanowires were a promising electrocatalyst for the hydrogen evolution reaction (HER) from water. Experimental Synthesis and characterizationTo synthesize 1D WO 3 , 2 g analytical grade sodium tungstate dihydrate (Na 2 WO 4 $2H 2 O) were dissolved in 45 ml distilled water under stirring at room temperature and 5 ml 3 M HCl was

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

“…Worth noting, results reported for WO 3 electrodes are mostly measured in acidic media. Under these experimental conditions tungsten oxide may also behave as electrocatalyst for hydrogen generation-as a result, the material working potential window should be narrowed [63,64], which would consequently lead to a limited performance of the electrode in terms of lower energy density. On the contrary, the WO 3 nanochannel layers are explored in this work in a neutral electrolyte, i.e.…”

Structure and thermal decomposition of ammonium metatungstate

“…One of their major applications is that tungsten oxides, metal tungstates, tungsten carbides or tungsten metal can be prepared from them, all of which are significant for various industries. Tungsten oxides can be used as catalysts [2][3][4][5], photocatalysts [6][7][8][9][10], gas sensors [11][12][13][14][15][16][17][18], chromogenic materials [19][20][21]; metal tungstates can be used among others as catalysts [22], pigments [23,24]; tungsten carbides are the hard components in cutting, drilling, tools [25][26][27] and they are also used as catalysts [28,29]; while tungsten metal is a key element in lighting industry [1,[30][31][32][33][34].…”

Photocatalytic properties of h-WO3 nanoparticles obtained by annealing and h-WO3 nanorods prepared by hydrothermal method

“…On the other hand, the hydrothermal synthesis is powerful method for preparing nanostructured WO 3 photocatalysts [13][14][15]. When SO 4 2-is added to the standard Na 2 SO 4 and HCl reaction mixture, it acts as a structure directing agent during the hydrothermal synthesis to obtain h-WO 3 nanorods [16]. Hence, in this study we prepared h-WO 3 nanoparticles by annealing (NH 4 ) x WO 3-y and h-WO 3 nanorods hydrothermally using Na 2 WO 4 , HCl, (COOH) 2 and NaSO 4 as precursors.…”