Selectivity towards H2 gas by flame-made Pt-loaded WO3 sensing films

In this work, unloaded WO3 and 0.25–1.0 wt% Pt-loaded WO3 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 (SSABET) of the nanoparticles was measured by nitrogen adsorption. Thick WO3 films (30 μm) on alumina substrates interdigitated with gold electrodes were prepared by spin-coating technique and tested for gas sensing towards H2, CO, C2H4 and 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 H2 sensing performances with a very high response, short response time and high selectivity towards CO, C2H4 and C2H5OH gases. The response (within seconds) and recovery (within minutes) times were very fast. It was found that 1.0 wt% Pt-loaded WO3 sensing films showed extremely excellent H2 sensing performances at 150 °C with the highest sensor response (S ∼ 1.34 × 105) and the highest selectivity compared to the other gases.