Gas Sensors Based On Micro/Nano Structures Of Reduced Graphene Oxide Nanosheets

Graphene has particular two-dimension plane structures and excellent properties, leading to its great potential in the field of gas sensing. Graphene has many unique properties, such as high carrier mobility, high specific surface area, excellent mechanical properties, stable physical and chemical property and room temperature electrical conductivity, which can be considered as ideal sensing materials. In our work, we studies two kinds of graphene based gas sensing materials by different chemical methods. In order to obtain a gas sensor which can work at room temperature with high sensitivity, rapid response and recovery, we fabricated porous reduced graphene oxide(r GO) and reduced graphene oxide(r GO) foam, and sensing detection of ammonia gases has also been studied. The obtained achievements are as following:(1) We have successfully prepared porous r GO by a combination of Photo-Fenton reaction and pyrrole reduction process. The resultant sensing materials exhibited a high sensitivity, rapid response and recovery and high selectivity for NH3 vapor. As the gas sensor exposes to NH3 vapor with the concentration of 1ppm, 20 ppm and 50 ppm, the resistance changes of porous r GO were 8.5 %, 13.2 % and 14.5 %, respectively. The response time and recovery time are less than 5 min and 3min, respectively. Porous r GO gas sensor showed excellent repeatablity. Furthermore, the response of porous r GO gas sensor to NH3 vapor was more than 3 times those of other analytes, indicating excellent selectivity property of the porous r GO sensors.(2) In our work, we have successfully prepared r GO/foam by a combination of GO deposition on polyurethane foam and pyrrole reduction processes. The resultant r GO/foam has a high sensitivity for NH3 vapor detection at room temperature. As the r GO/foam exposes to NH3 vapor with the concentration of 50 ppm, the resistance changes of gas sensor is 3.67 %. The response time is 8 min and recovery time is 4 min. The response of r GO/foam gas sensor to NH3 vapor shows more than 2 times those of other analytes.In this thesis, we studies two kinds of gas sensing materials based on graphene, which can be facilely produced with low cost characterisitics. The assembled sensing devices show excellent sensitivity, repeatability and selectivity to NH3 vapor at room temperature, revealing their great potential for gas detection.