A route to detect H2 in ambient conditions using a sensor based on reduced graphene oxide

Graphene Oxide (GO) is considered an ideal candidate for the fabrication of hydrogen gas (H-2(g)) sensors due to its excellent capabilities for direct wiring, thanks to the presence of functional groups, which provide an opportunity to modify its chemical functionalities. In this study, we have fabricated a H-2(g) sensor based on the precise positioning of GO flakes across sputtered aluminium-doped ZnO (AZO) electrodes on a glass substrate using a positive dielectrophoretic force (DEP). GO flakes assembly was performed between AZO electrodes gap of 4 mu m and optimized by controlling the DEP parameters. A chemical reduction using a solution of 10 mM sodium borohydride was used to enhance the conductivity of the GO flakes up to two orders of magnitude. The arrangement of the GO flakes, the efficiency of the reduction process, the morphology and the surface potential of these was analyzed by Atomic Force and Kelvin Probe Microscopies. A reduced Graphene Oxide (rGO) work function in the range of 4.7-4.9 eV was obtained. Moreover, the H-2(g) response of rGO/AZO sensor was studied by two types of tests. First test consists of a single 10 min exposure of pure H-2(g), collecting the IV directly data in order to obtain the sensitivity of the rGO to be of similar to 100 % at 1 V. Second test consists of a batch of different time exposures to analyze the stress performance and the saturation level of the sensor. Finally, the impact of the ambient conditions on our sensor sensitivity was studied. (C) 2020 Elsevier B.V. All rights reserved.