Effects of Catalyst on Gasochromic Properties in Tungsten Oxide Films

Abstract

Effects of catalyst on gasochromic properties in tungsten oxide films were investigated. Amorphous WO3 films coated with Pd and Pt catalysts were prepared on SiO2 substrates by employing reactive RF magnetron sputtering. To quantitatively estimate the thickness of the catalytic layer, the Rutherford backscattering spectroscopy (RBS) was employed. The coloration behavior was examined by measuring light transmittance of the samples exposed to 1% hydrogen diluted nitrogen gas. The field emission scanning electron microscope (FE-SEM) showed that particles with a dozes nm diameter of Pd and with a few nm of Pt grew on the surface of silicon substrates at beginning of deposition. The continuous catalytic layers were observed with increasing the amounts of more than 2 nm for Pd and 0.2 nm for Pt catalysts, respectively. When the continuous layers formed on WO3 surface, the excellent gasochromic properties were obtained. The results indicated that Pt catalysts were suitable for high sensitive hydrogen sensors consisting of gasochromic WO3 films.