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.