Recently, the demands for the hydrogen gas is intense for the clean and renewable energy source to replace the fossil fuels. The hydrogen is applicable for the various areas such as stationary/mobile fuel cells, space industry, and biomedical fields. The most serious concern for the hydrogen usage is safety issue. Even though the hydrogen itself could be utilized as a clean and high efficient energy source, the gas has dangerous factors such as high diffusion coefficient (0.16cm2/s in air), low ignition energy (0.018 mJ), high combustion heat (285.5 kJ/mol). With above characteristics, hydrogen is highly volatile and explosive above only 4% of concentration which requires careful handling. Moreover, detection of colorless, odorless hydrogen with human sense is almost impossible. Consequently, reliable detection of hydrogen leakage is necessary for the related applications.
In this work, we demonstrated optical detection of hydrogen for the safety application with cost effective sol-gel based process. The tungsten trioxide (WO3) as a gas chromic metal and a palladium (Pd) as catalyst are utilized as chemochromic hydrogen detection in a core-shell like structure to provide the enlarged surface area.