Hydrogen Gas Sensing Using Palladium-Graphene Nanocomposite Material Based on Surface Acoustic Wave

We report the fabrication and characterization of surface acoustic wave (SAW) hydrogen sensors using palladium-graphene (PdGr) nanocomposite as sensing material. The Pd-Gr nanocomposite as sensing layer was deposited onto SAW delay line sensor-based interdigitated electrodes (IDTs)/aluminum nitride (AlN)/silicon (Si) structure. The Pd-Gr nanocomposite was synthesized by a chemical route and deposited onto SAWsensors by air-brush spraying. The SAW H-2 sensor using Pd-Gr nanocomposite as a sensing layer shows a frequency shift of 25 kHz in 0.5% H-2 concentration at roomtemperature with good repeatability and stability. Moreover, the sensor showed good linearity and fast response/recovery within ten seconds with various H-2 concentrations from 0.25 to 1%. The specific interaction between graphene and SAW transfer inside AlN/Si structures yields a high sensitivity and fast response/recovery of SAW H-2 sensor based on Pd-Gr/AlN/Si structure.