Investigation of Electrical Hydrogen Detection Properties of Pt/WO3 Thin Films Prepared by Sol-Gel Method

Platinum (Pt)nanoparticle-dispersed tungsten trioxide (WO3) thin film is a gasochromic material that changes color from transparent to blue in an H-2 gas atmosphere. The electrical conductivity of Pt-nanoparticle-dispersed WO3 is dependent on inserted protons and electrons, though the material is insulator in air, because these electrons and protons work as electrical carriers in WO3. In this study, Pt-nanoparticle-dispersed WO3 thin films were prepared using the sol-gel process, and the optical and electrical properties were evaluated in an atmosphere with or without H-2 gas. Pt/WO3 thin films prepared at 400 degrees C showed the largest change in electrical conductivity when exposed to 1% H-2 gas compared with thin films prepared at other temperatures. The electrical conductivity of the film was dependent on an H-2 gas concentration in the range from 100 ppm to 1%. Pt/WO3 thin films prepared by the sol-gel process are expected to be used for H-2 gas sensor devices due to the linear relationship between the electrical conductivity and H-2 gas concentration.