| Graphene is composed of one-atom-thick planar sheets of carbon atoms that aredensely packed into a honeycomb crystal lattice. It has attracted worldwide researchboom. In recent years, as people’s quality of life, industrial production and livingenvironment safety, environmental monitoring, and medical fields requires thecontinuous improvement, the gas sensor performance requirements are also rising. Soresearch and development based on the new high-performance gas sensors sensitivematerial become important. The sensing materials play an important role in theperformances of gas sensors. Gurrently, much attention has been paid on preparationof NO2sensors based on semiconductor materials, which exhibit some obviousdisadvantages including high operating temperature and relatively high detectionlimit. Graphene has shown many unique properties, such as high specific surface area,high carrier mobility, excellent mechanical property, stable physical and chemicalproperty and room temperature electrical conductivity, which can make up for theshortcomings of the semiconductor sensing materials. However, the low sensitivity,slow response and recovery and poor selectivity have to be the bottleneck in thedevelopment of NO2sensors based on pure grapheme. In order to obtain a sensor which can work at room temperature with highsensitivity, rapid response and recovery and high selectivity, this paper presentsgraphene sensors were loaded by tin oxide and noble metal, regulating electrontransport capacity, improving the type and number of active sites on the surface,enhancing the recognition ability and the adsorption capacity to NO2. In this work westudy the sensitive of graphene materials, and reveal the relationship between themicro-environment of the surface on the sensitive materials and gas sensingproperties, and explore the sensitive mechanism. The innovative achievements are asfollows.1. Using Hummers and liquid phase separation method to prepare oxidizedgraphene and graphene oxide reduction and examine its NO2gas sensingcharacteristics and analysis of its sensitive mechanism. Gas sensing propertiesanalysis showed that oxide reduction showed low sensitivity, slow response andrecovery.2. rGO/Au hybrid nanomaterialas has been systhesised by hydrothermal methodwhich can change the semiconductor properties of grapheme and control the carriertransport ability to realize the response reply quickly, the mechanism of Au has beendicussed. By adjusting the added amount of HAuCl4during the synthetic process ofthe reaction, sensitivity characteristics successfully is optimized the material at a lowtemperature state. 3. Using the reactant concentration ratio adjustment methods, rGO/SnO2wereprepared by hydrothermal synthesis as different proportions. The improving of theactive sites on the surface of grapheneresults though load SnO2to improve theadsorption properties of the target gas, so the materials that can work at roomtemperature with high sensitivity were obtained.4. Different ratios of rGO/SnO2/Au has been prepared with hydrothermalsynthesis technique mainly work on NO2at room temperature, by adjusting the ratioof HAuCl4contral the size and quantity of Au nanoparticles, prepare. Thetransmission characteristics of electrons among grapheme, SnO2and goldnanoparticles have also been discussed.In this paper, rGO metal oxide nanocomposites has been prepared byhydrothermal method, compared with rGO on the gas sensing characteristics and gassensing mechanism of the product in detail is discussed. The results showed that:loading noble metal or metal oxide is an ideal method to improve gas sensingproperties, the nanocomposite material based on rGO has a low detection, highsensitivity and response characteristics of a short response time, compared to othergraphene-based materials, gas sensors, displays a more excellent gas sensingcharacteristics. In this paper, a lot of basic research has been made on for graphene covered withmetal oxide or noble metal and gas sensing properties to further explore theirpotential applications. |
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