Combining a granular thin film of PtO-Pt with a film of TiO_2 or SnO_2 nanoparticles, we have designed and successfully prepared a new type of hydrogen sensors with a dual-layer structure. Microstructures of the prepared sensors were characterized by TEM and HRSEM. Measurements on the sensitivities of the prepared sensors to 4.0% H_2 in air reveal that the sensitivity of TiO_2/PtO-Pt is about 70% AT 200 ℃, while that of SnO_2/PtO-Pt at 100℃ is up to 92%. The high sensitivities of the prepared dual-layer films sensors at relatively low temperature are derived from the catalytic function of the PtO-Pt granular film. In addition, both TiO_2/PtO-Pt and SnO-2/PtO-Pt show a high selectivity to hydrogen in air.

Key words: TITANIUM DIOXIDE, TIN OXIDE, RECOMBINATION, THIN FILMS, PLATINUM OXIDE, PLATINUM, NANOPHASE MATERIALS, SCANNING ELECTRON MICROSCOPES, TRANSMISSION ELECTRON MICROSCOPY