▎ 摘　　要

In this work, we study the effect of palladium nanoparticles (PdNPs) functionalization on the hydrogen sensing performance of devices based on graphene (GR). Microwave irradiation has been used to directly synthetize PdNPs onto GR sheets. PdNPs-GR devices, realized using palladium coverage loads from 0.5 mg up to 10 mg, have been investigated at Room Temperature (RT). Experiments show that an optimal value of the palladium coverage exists, corresponding to a 5 mg loading, that results in a more sensitive and faster device with a gas response of similar to 30% when exposed to 1% H-2. A possible operating mechanism based on the different chemical and physical properties of the alpha and beta phase of palladium hydride layers that grow as a result of reaction between hydrogen and PdNPs-GR, is suggested. The main outcome of this study is to show that it is possible to tune GR sensitivity towards hydrogen suitably adjusting the Pd loading confirming, in turn, that NPs functionalization can be an effective means to tune the graphene physical properties. (C) 2017 Elsevier B.V. All rights reserved.