Research About Preparation And Gas Sensing Properties Of Graphene/Semiconductor Oxide Composite Material

Gas sensors based on semiconductor oxide material with excellent gas-sensing properties take a lot of market share. In terms of the present research situation, there is room for improvement of comprehensive gas sensitive properties of gas sensors based on single kind of semiconductor oxide. In this dissertation, we improved gas sensing properties of semiconductor oxides(tin oxide and zinc oxide) through introducing graphene which possesses good electrical properties.The specific research contents and results are shown as follows:First of all, a novel discoid crystal of rutile Sn O2 modified by reduced graphene oxide(r GO) was prepared through a facile one-step hydrothermal method. In the experiment, the GO was prepared with Hummers’ method, and was used as one of the main precursors and reduced successfully during the hydrothermal reaction. Uniform discoid rutile Sn O2 monocrystal with rough surface, a diameter of approximately 100 nm and a center thickness of 40 nm were anchored on both sides of r GO nanosheets. The Sn O2/r GO composite exhibited preferential detection toward NO2 with super gas sensing properties: high response, the response of the sensor to 1 ppm NO2 at 75℃ as nearly 700; low detection limit, the response of the sensor to 50 ppb NO2 at 75℃ reached 2.9; good selectivity and reproducibility.Secondly, we synthesized flowerlike Zn O reduced by r GO with precursor, octan zinecnaty, ammonium hydroxide and GO solution through water bath heating and calcination at high temperature for a short period of time. Both of the experimental materials and experimental process are simple and no poison derivatives were produced during the experiment. r GO layers can be detected among the flowers and petals of Zn O. The results of gas sensing test demonstrated that Zn O /r GO composite exhibited preferential detection toward NO2 with super gas sensing properties: high response, the response of the sensor to 50 ppb NO2 at 100℃ as about 13.4; low detection limit, the response of the sensor to 5 ppb NO2 at 100℃ reached 6.65; good selectivity and reproducibility; low affection of humidity on response.In conclusion, this work proved that this dissertation proved the feasibility to obtain gas sensitive materials with high performance through composite reaction of graphene and semiconductor oxide. Heterojunction resulted from the introduction of r GO may play the main role in the optimization of gas sensing properties.