High-performance humidity sensors based on reduced graphene oxide sheets decorated with cobalt and iron doped ZnO nanorods

Humidity sensors based on doped zinc oxide (ZnO) / reduced graphene oxide (rGO) composites have shown potential since the doped ZnO/rGO material is sensitive to changes in humidity. Here, the present work report of one-step hydrothermal synthesis of ZnO/rGO and doped ZnO/rGO nanocomposites where ZnO has been doped with cobalt and iron at concentrations of 2 %. X-ray diffraction validates the substitution of transition metal cations in the ZnO lattice. Scanning electron microscopy depicts a graphene-layered structure with intact ZnO rods. Humidity sensors based on Fe doped ZnO/rGO composite showed response and recovery periods of 27 s and 24 s, respectively, in the range of 11–97 % relative humidity. The composite has the sensitivity of 2.2 kΩ at 100 Hz which is the highest as compared to ZnO/rGO and Co doped ZnO/rGO. Because of the greatest sensitivity and quick reaction and recovery timer, Fe doped ZnO/rGO composites appear to be ideal for use as humidity sensors. [Display omitted] •Doped ZnO-rGO composites.•Synthesis: hydrothermal method.•Notable Humidity sensitivity.