Pd/Cu Nanowires Coated SAW Sensor for Fast Hydrogen Gas Sensing

Fast detection and monitoring for hydrogen (H 2 )is essential in H 2 energy application. A new surface acoustic wave (SAW)H 2 sensor was proposed in this contribution employing supperlattice-structured palladium and copper nanowires(Pd/Cu NWs)depositing along the SAW propagation path and a differential oscillator structure. The adsorption in Pd/Cu NWs towards H 2 molecules modulates the SAW propagation, and the corresponding shifts in oscillation frequency proportional to gas concentration was collected as the sensor signal. The larger surface-to-volume (S/V)ratio and porous structure of the Pd/Cu NWs synthesized by wet-chemical approaches fasten the response and recovery time in H 2 -sensing behaviors, which was confirmed by characterizing the developed SAW sensors built with PdCu NWs and delay line pattern. Very fast response time and recovery time of less than 3s were achieved successfully at room temperature, also, the obtained sensitivity and detection limit are evaluated up to 1.5kHz/% and 7 ppm.