▎ 摘　　要

In this work, the important role of electronic changes taking place at the palladium (Pd)-graphene interface during hydrogen sensing has been established by studying hydrogen sensing behaviour of Pd and Pd/graphene composite layers with different Pd thicknesses. CVD-grown single layer graphene and Pd nanoparticulate layers deposited by thermal evaporation method were used in this study. A drastic change in hydrogen sensing behaviour was observed in Pd/graphene samples as the topography of Pd layer changes from a continuous film to a discontinuous nanoparticulate layer and finally to isolated Pd nanoparticles. In case of Pd nanoparticles/graphene samples having isolated nanoparticles, the observed sensing behaviour is due to change in electronic nature of Pd/graphene interface on hydrogen exposure. Relatively lower value of work function of Palladium hydride in comparison to graphene results in electron migration and compensation of p-type charge carriers in graphene on hydrogenation of Pd. The hole doping at Pd-G interface is also confirmed by Raman spectroscopy. The Pd/graphene interface sensor with 10 nm of Pd thickness shows enhanced sensing response (at 2% hydrogen) of 51.4% with faster response time (6 s) in comparison to sensing response (41%) and response time (56s) in Pd thin film sensor having similar thickness. (C) 2014 Elsevier B.V. All rights reserved.