Palladium Nanoparticles and Bimetal Palladium Layers

In the present work, two approaches (i) nanoparticle route and (ii) bimetal layer route have been employed to enhance the Pd-H interaction. Size-selected, monodisperse Pd nanoparticles having well-defined size distributions have been synthesized. In Pd nanoparticles, a unique pulsed like hydrogen sensing response has been obtained in which electrical resistance increases due to electronic effect sharply followed by a sudden decrease due to geometric effect when the hydrogen is switched on. The hydrogen sensing response is studied at different H2 concentrations and measurement temperatures in size-selected and monodisperse Pd nanoparticles. Two types of sensing behaviours are observed as a function of H2 concentration: (i) a normally observed 'saturated' response and (ii) a 'pulsed' response. In the second approach of using bimetal layer, Cu and Ag thin film has been deposited onto Pd layers and hydrogenation properties have been studied. In Ag/Pd bimetal layer system, the effect of converting the metal over layer from thin film (TF) to metal nanoparticle (NP) layers has been investigated.