Nanocrystalline Pt-doped TiO2 thin films prepared by spray pyrolysis for hydrogen gas detection

Nanostructured pure and Pt-doped TiO₂ thin films were prepared by chemical spray pyrolysis technique. Aqueous solution of TiCl₃·6H₂O (0·01 M) was chosen as the starting solution for the preparation of pure TiO₂ thin film. Aqueous solutions of PtCl₆·6H₂O (0·01 M) and TiCl₃·6H₂O (0·01 M) were mixed in volume % of 1 : 99, 2·5 : 97·5 and 5 : 95 respectively to obtain Pt-doped TiO₂ thin films. The solutions were sprayed onto quartz substrate heated at 350 °C temperature to obtain the films. These thin films were fired for one hour at 550 °C. The sensing performance of these films was tested for various gases such as LPG, H₂, CO₂, ethanol, NH₃ and Cl₂ (1000 ppm). The Pt-doped TiO₂ (1 : 99) was observed to be most sensitive (572) to H₂ at 400 °C with high selectivity against other gases. Its response time was short (10 s) and recovery was also fast (14 s). To understand the reasons behind the gas-sensing performance of the films, their structural and microstructral properties were studied using X-ray diffraction and electron microscopy (FE–SEM and TEM), respectively. Thicknesses of all these samples were determined using Surface Profiler. The results are interpreted.