Hydrogenation and Dehydrogenation of Hydrophobic Pd-Capped Vertically Aligned Porous Ti Nanoflake Thin Film

Abstract

Hydrophobic palladium-capped vertically aligned porous titanium nanoflake (Pd/Ti) thin film has been grown on a Si substrate by DC-sputtering. The hydrogenation (0.5 bar) and dehydrogenation (100°C) kinetics of the Pd/Ti thin film have been studied in terms of their structural, morphological and optical properties. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and UV–Vis–NIR spectroscopy findings endorsed the hydrogen absorption and desorption in the Pd/Ti thin film. It was observed that the optical reflectance R decreased after hydrogenation due to the formation of dark gray-colored TiH2. Further, an increase in R was found after dehydrogenation and it became nearly equal to the R value of the as-deposited sample, which confirmed the reversible nature of Pd/Ti film towards hydrogen absorption and desorption. These investigated hydrogenation and dehydrogenation properties of the Pd/Ti thin film make this material interesting for optical hydrogen sensing and switching applications.