Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

Palladium (Pd)-based hydrogen (H₂) gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H₂ gas sensors; however, all the sensors must be powered through an external battery. We report here an H₂ gas sensor that can detect H₂ by measuring the output voltages generated during contact electrification between two friction surfaces. When the H₂ sensor, composed of Pd-coated ITO (indium tin oxide) and PET (polyethylene Terephthalate) film, is exposed to H₂, its output voltage is varied in proportion to H₂ 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 H₂ concentration increases. Reproducible and sensitive sensor response was observed up 1% H₂ exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.