Fabrication of a novel 2D-graphene/2D-NiO nanosheet-based hybrid nanostructure and its use in highly sensitive NO2 sensors

A highly sensitive gas sensor based on novel hybrid structures composed of 2D graphene and 2D NiO nanosheets (NSs) is fabricated using a low-cost, low temperature and large area scalable solution-based process. The highly developed hierarchically porous structures of 2D NiO sheets are grown on reduced graphene oxide (RGO) surfaces. Sensors fabricated with hybrid structures showed a responsivity and sensitivity two orders higher than that of a NiO NS alone toward NO2 even at 1 ppm level. This is attributed to the effective carrier transfer from NiO NS to graphene and to the well-developed 2D NiO structure. The sensing results are similar when reducing gases such as H2, NH3 and H2S are tested, but the responsivity toward NO2 was highest among all the gases tested.