Selectivity towards H 2 gas by flame-made Pt-loaded WO 3 sensing films

Abstract

In this work, unloaded WO3and 0.25-1.0 wt% Pt-loaded WO3powders were produced by flame spray pyrolysis (FSP) and structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). The BET surface area (SSABET) of the nanoparticles was measured by nitrogen adsorption. Thick WO3films (30 μm) on alumina substrates interdigitated with gold electrodes were prepared by spin-coating technique and tested for gas sensing towards H2, CO, C2H4and C2H5OH gases at concentrations ranging from 0.01 to 1 vol% in dry air with operating temperatures ranging from 150 to 300 °C. The sensing films exhibited excellent H2sensing performances with a very high response, short response time and high selectivity towards CO, C2H4and C2H5OH gases. The response (within seconds) and recovery (within minutes) times were very fast. It was found that 1.0 wt% Pt-loaded WO3sensing films showed extremely excellent H2sensing performances at 150 °C with the highest sensor response (S ∼ 1.34 × 105) and the highest selectivity compared to the other gases. © 2011 Elsevier B.V. All rights reserved.