The hydrogen gas sensors were developed successfully using flame-made platinum-loaded titanium dioxide (Pt-loaded TiO2) nanoparticles as the sensing materials. Pt-loaded TiO2 thin films were prepared by spin-coating technique onto Al2O3 substrates interdigitated with Au electrodes. Structural and gas-sensing characteristics were examined by using scanning electron microscopy (SEM) and showed surface morphology of the deposited film. X-ray diffraction (XRD) patterns can be confirmed to be the anatase and rutile phases of TiO2. High-resolution transmission electron microscopy (HRTEM) showed that Pt nanoparticles deposited on larger TiO2 nanoparticles. TiO2 films loaded with Pt nanoparticles were used as conductometric sensors for the detection of H2. The gas sensing of H2 was studied at the operating temperatures of 300, 350, and 400°C in dry air. It was found that 2.00？mol% Pt-loaded TiO2 sensing films showed higher response towards H2 gas than the unloaded film. In addition, the responses of Pt-loaded TiO2 films at all operating temperatures were higher than that of unloaded TiO2 film. The response increased and the response time decreased with increasing of H2 concentrations. 1. Introduction Metal oxide nanopowders offer promising research materials because of their wide range of applications. Many studies have focused on enhancing the performance of gas sensors. They were synthesized by different techniques such as the modified sol-gel method [1], thermal plasma [2], hydrothermal [3], and flame spray pyrolysis [4, 5]. Flame spray pyrolysis (FSP) is one-step synthesis method that is suitable for large-scale production of noble metal-metal oxide nanocomposites [6–8]. Hydrogen gas is an important gas for clean energy sources, highly flammable, and burnable in air at a very wide range (4–75% by volume) [9–11]. However, its presence due to leakage at a sufficient high concentration together with oxygen in air will cause explosion. Moreover, H2 cannot be detected by human senses when it leaks. Therefore, semiconducting Pt-loaded TiO2 is one of the most promising candidates for flammable gas detection due to its advantages including low cost, high sensitivity, fast response, simplicity of use, and ability to detect a large number of gases. In this study, we report the synthesis of unloaded TiO2 and Pt-loaded TiO2 by FSP and study the effect of Pt catalyst dispersion in TiO2 nanopowder surface on hydrogen gas-sensing behaviors due to the fact that Pt nanoparticles dispersed on the TiO2 surface can act as electron sinks and result in a decrease in
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