Influence of graphene growth temperature by chemical vapour deposition on the hydrogen response of palladium–graphene junction

The hydrogen sensing by palladium-graphene junction was dependent on the atmospheric pressure chemical vapour deposition growth temperature of the graphene films. The growth temperature window adopted in this study was 900–1000 °C, and the hydrogen sensor performance of the palladium–graphene junction (0.5–2.0% H2 in air) was studied in the temperature range 30–150 °C. Raman spectroscopy study with the as grown graphene films revealed the multilayer nature and the Pd–graphene planar structure showed a temperature dependent n- to p-type conductivity change in presence of hydrogen. Such a conductivity transition in presence of a reducing gas like hydrogen was experimentally studied in detail, and the hydrogen sensor results were correlated with the multilayer character of the graphene thin film, which induces hydrogen intercalation between the graphene layers.