Stability of Tungsten Oxide Nanoparticles in Different Media

Abstract

Tungsten oxide (WO3) nanoparticles were synthesised by a simple chemical precipitation method in various media, such as acidic, basic and neutral. Hydrochloric acid and sodium hydroxide were used to maintain the different pH levels and tungstic acid was used as the precursor for the synthesis of tungsten oxide. The resultant nanoparticles were studied by different characterisation techniques. Powder X-ray diffraction shows that the average crystallite size of the WO3 is about 13 nm and exhibits stable orthorhombic phase for different pH values. Particle size and the surface morphology of the synthesised material were studied by TEM analysis. Chemical composition and surface area of the nanoparticles were studied by FTIR and BET measurements. Optical properties of the synthesised nanoparticles were studied by UV-Vis absorption and photoluminescence spectroscopy. Band gap (~2.7 eV) of the synthesised WO3 was investigated from the optical absorption spectra. At room temperature, a strong PL blue emission peak at ~440 nm was observed for the synthesised tungsten oxide nanomaterials. Thermal stability of the synthesised material was studied by TG/DTA analysis. Cyclic voltammetry illustrated the electrochemical response of the WO3 nanoparticles using KCl as electrolyte. The peak separation of 182 mV, 153 mV and 77 mV for the acidic, basic and neutral media were observed. Thus it was confirmed that, tungsten oxide has a low peak separation, a fast reaction rate and electron transfer rate in neutral medium.

Effect of calcination temperature induced structural modifications on the photocatalytic efficacy of Fe2O3–ZrO2 nanostructures: mechanochemical synthesis

“… 27 A midrange band at 1639.39 cm −1 was noted, possibly originating from the bending of H–O–H coordinated H 2 O molecule. 28 Peak at 1379.79 cm −1 was ascribed to the presence of surface –OH groups in M–OH (either Fe(OH) 2 or Zr(OH) 4 ). 26 An additional peak emerged at 1219.15 cm −1 , which may also be attributed to the vibrations of M–OH (either Fe(OH) 2 or Zr(OH) 4 ).…”

Visible light and dark-driven degradation of palm oil mill effluent (POME) over g-C3N4 and photorechargeable WO3

“…Others showed that WO 3 nanoparticles indicated the presence of absorption peaks at 320 nm (2.7-2.9 eV) (Shukla et al 2016). By comparing the results from Ragunathan et al (2015), the absorption peaks was depicted a characteristic absorption peak at 285 nm. The results supported the level of absorption of light of both photocatalysts, which have been strongly modi ed by the calcination temperature that may have been caused by the growth of crystal structure onto its surface; this then aids their incident light irradiation.…”

Solvent free fabrication and thermal tuning of copper oxide-zirconium dioxide nanocomposite for enhanced photocatalytic efficacy

“…the bending of H-O-H coordinated water molecule[23]. The presence of surface -OH groups in M-OH (either Cu(OH) 2 or Zr(OH) 4 ) was revealed by the absorption peak at the wavelength 1395.63 cm −1[22].…”