Hybrid Hydrogen Sensor Based on Pd/WO 3 Showing Simultaneous Chemiresistive and Gasochromic Response.

The gasochromism of WO 3 , wherein the color of the material changes according to the reaction of gas, can immediately allow for the determination of the presence of hydrogen by the naked eye. We have also developed a hybrid hydrogen sensor for WO 3 , a metal oxide, that can simultaneously utilize its gasochromic response and resistance to hydrogen. Because the proposed sensor has a transparent electrode on a glass substrate, it is a structure that can not only reveal the change in resistance but also more clearly illustrate the gasochromic response. A hybrid sensing demonstration in a hydrogen leak environment was successfully performed to verify a sensor that was capable of utilizing the resistive and gasochromic response of WO 3 .