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

Abstract

In this work, unloaded WO 3 and 0.25–1.0 wt% Pt-loaded WO 3 powders 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 ( SSA BET) of the nanoparticles was measured by nitrogen adsorption. Thick WO 3 films (30 μm) on alumina substrates interdigitated with gold electrodes were prepared by spin-coating technique and tested for gas sensing towards H 2, CO, C 2H 4 and C 2H 5OH 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 H 2 sensing performances with a very high response, short response time and high selectivity towards CO, C 2H 4 and C 2H 5OH gases. The response (within seconds) and recovery (within minutes) times were very fast. It was found that 1.0 wt% Pt-loaded WO 3 sensing films showed extremely excellent H 2 sensing performances at 150 °C with the highest sensor response ( S ∼ 1.34 × 10 5) and the highest selectivity compared to the other gases.