Study of a New Hydrogen Gas Sensor Synthesized With a Sputtered Cerium Oxide Thin Film and Evaporated Palladium Nanoparticles

A new hydrogen (H2) gas sensor, synthesized with a radio frequency (RF) sputtered cerium oxide (CeO2) thin film and rapid thermal evaporated palladium (Pd) nanoparticles (NPs), is fabricated and reported herein. The employed Pd NPs can effectively increase the surface area/volume ( SA/V) ratio and catalytic reactivity of Pd metal, thereby substantially enhancing the adsorption effect of hydrogen molecules on the device surface and improving the related sensing performance. Energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the related properties of the studied device. Experimentally, a high sensing response of 120.2 under 1% H2/air gas at 350 °C with a relatively shorter response (recovery) time of 5 s (17 s) is obtained. The studied Pd NP/CeO2-based sensor device shows wide operating ranges of temperature (200 °C-400 °C) and hydrogen concentration (10 ppm-1% H2/air). A thermodynamic analysis employed to study the surface coverage of hydrogen molecules is reported in this work. The studied sensor device also exhibits the advantages of a simple structure, easy fabrication process, and relatively low cost.