Hydrogen induced resistance and optical transmittance of pulsed laser deposited Pd/Mg thin films

Abstract

The hydrogen detection is an important issue for the societal acceptance of H₂ as energy carrier. In present research work, we have investigated hydrogen sensing and optical properties of Pd/Mg thin films on glass substrate deposited by pulsed laser (PL). As-deposited thin films have been exposed (hydrogenation) to H₂ gas (2 bar) at room temperature in a hydrogenation unit. Hydrogenated and dehydrogenated (at different temperatures) samples have been characterized using X-ray diffractometer (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis-NIR spectrophotometer, atomic force microscopy (AFM). XRD results confirm the formation of hydride (MgH₂) tetragonal phase upon hydrogenation of Pd/Mg films. Hydrogen induced resistance response of Pd/Mg films has been measured in-situ during hydrogenation/dehydrogenation process by using two- probe electrical method. The response time (sensitivity) of Pd/Mg films for hydrogen gas is ~ 60 s at room temperature. The study of optical transmittance of hydrogenated Pd/Mg films indicates their switchable mirror behavior.