Highly Selective and Extensive Range Room Temperature Hydrogen Gas Sensor Based on Pd-Mg Alloy Thin Films

In this study, MgPd alloy thin films were deposited on a glass substrate using dc/RF magnetron sputtering technique with varying sputtering power (30-60 W) of Pd target to achieve different compositions of alloy. X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS) analyses provide the crystalline structure and elemental composition of the MgPd alloy thin films, respectively. The surface morphology study through field emission scanning electron microscopy (FE-SEM) reveals nanoflakes. Gas sensing study reveals that the sensitivity of the Mg65Pd35 alloy thin film sensor is 3.41% for 500 ppm and 13% for 1 bar of hydrogen (H2) at room temperature (RT). The response/recovery times of the sensor are 5 s/3 min and 85 s/6 min for 1 bar H-2 gas and 500 ppm H-2, respectively. A remarkable selectivity toward the H-2 gas is observed in comparison to other gases such as CO, NO2, and NH3. Long-term stability was observed even with increased Pd composition over multiple hydrogenation/dehydrogenation cycles. These findings suggest that Pd-capped MgPd alloy thin films are promising for the applications of highly durable, selective, cost-effective, and room-temperature hydrogen gas sensors.