Impact of further thermal reduction on few-layer reduced graphene oxide film and its n-p transition for gas sensing

Hydrazine-reduced graphene oxide (RGO) film was further annealed for gas sensing investigation. Pristine RGO film with an initial n-type property underwent an n-p transition on dynamic exposure to NO2 gas. After annealing at 300 degrees C, RGO film became p -type semi -conducting while the p-n transition behavior did not appear when immersed into target gases. Sensing mechanisms were studied combining with multiple characterization techniques such as SEM, EDS, XRD, Raman and FTIR by researching film differences before and after annealing. Interfering factors including operational temperature and relative humidity were contrastively analyzed as well. Besides, the effect of thermal annealing on relationship between flow rate of background gas and electric resistance variation was considered closely related to structural deformation of RGO film. The detailed and systematic investigation would enrich available gas -sensing mechanisms of RGO based sensors, and put forward some new scientific issues to be further studied, such as suppression of n-p or p-n transition and the concrete influence mode of film deformation on gas sensing. (C) 2016 Elsevier B.V. All rights reserved.