Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

Palladium (Pd)-based hydrogen (H-2) gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H-2 gas sensors; however, all the sensors must be powered through an external battery. We report here an H-2 gas sensor that can detect H-2 by measuring the output voltages generated during contact electrification between two friction surfaces. When the H-2 sensor, composed of Pd-coated ITO (indium tin oxide) and PET (polyethylene Terephthalate) film, is exposed to H-2, its output voltage is varied in proportion to H-2 concentration because the work function (WF) of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H-2 concentration increases. Reproducible and sensitive sensor response was observed up 1% H-2 exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.