Structural, optical and acetone gas sensing properties of WO<inf>3</inf> and Gd3+ doped WO<inf>3</inf> nanostructures

Abstract

In present work, structural, optical and acetone gas sensing properties of WO 3 and 5% Gd3+ doped WO 3 nanostructures have been studied. The simple cost-effective acid precipitation method was adopted. Synthesized samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and diffuse reflectance spectroscopy (DRS) techniques. XRD results confirmed the formation of monoclinic phase for WO 3 and Gd3+ doped WO 3 nanostructures which were further supported by Raman studies. It was observed that the crystallite size of WO 3 nanostructures was decreased with Gd3+ doping. FESEM micrographs showed nanoplate type morphology of pure and Gd3+ doped WO 3 nanostructures. EDX confirmed the presence of Gd dopant in WO 3 nanostructures. A broadening and shifting of Raman stretching modes in Gd3 + doped WO 3 nanostructures was observed. DRS results showed a red shift in band gap with Gd doping. For acetone gas sensing properties, the powder samples were applied as thick film onto alumina substrate and tested at different operating temperatures. The results showed that the optimum operating temperature of both the gas sensors was 350°C. At optimum operating temperature, the response of WO 3 and Gd3+ doped WO 3 gas sensor towards 50 ppm acetone was found to be 5 and 16.5. The investigations revealed that the addition of Gd3+ as a dopant enhanced the sensing response of WO 3 nanostructures appreciably.