Synthesis And Gas Sensing Properties Of RGo-ZnO Based Composite Nanofibers

As an important tool to detect the composition and concentration of gas,gas sensor plays an important role in many fields.MOS sensor has many advantages,such as higher sensitivity,shorter response time,and lower cost and so on.It is used as a gas sensing material in many scientific researches.The ZnO nano material with wide band gap and large exciton binding energy is an excellent gas sensing material.However,the problems of higher temperature and poorer selectivity of ZnO still need to be solved.Graphene has attracted a lot of attention because of its excellent properties and potential applications since the discovery of it in 2004.In this paper,Zn O nanofibers were used as basic materials,and the gas sensing properties were improved by the combination of trace graphene and metal doping.The main research work is as follows:1.The ZnO nanofibers were synthesised by electrospinning.The rGO(reduced graphene oxide)/Zn O composite nanofibers were synthesised by two methods.One method is to synthesize the nano composite fibers by hydrothermal synthesis with the burning ZnO nanofibers and rGO solution.The other method is to directly mix trace rGO in the ZnO precursor solution,and obtain the r GO/ZnO composite nanofibers after calcination.The results showed that the gas sensing properties of rGO-ZnO composite nanofibers synthesized by two step hydrothermal method and electrospinning method were obviously improved to H2 S gas.At 200?,the sensitivity of rGO modified ZnO nanofiber is 6.8 to 1ppm H2 S.And it is 2.7 times of ZnO nanofibers.The sensitivity of rGO/ZnO nanofibers is 20.6 to 1ppm H2 S.And it is 8.2 times of ZnO nanofibers.At the same temperature,the sensitivity of rGO-Zn O composites were not significantly improved to other interfering gases.It showed that the selectivity of the composite gas sensing materials synthesized by two step hydrothermal method and direct spinning method were improved obviously.2.A study on the gas sensing properties of the rGO and Cu doped ZnO composite nanofibers.The rGO modified Cu doped Zn O nanofibers were synthesized by hydrothermal method,and the rGO/Cu doped ZnO nanofibers were synthesized by electrospinning.And the gas sensing properties of the materials were tested.It was found that the sensitivity of rGO modified Cu doped ZnO nanofibers was 43 to 1ppm H2 S at 200.The sensitivity of rGO/Cu doped ZnO nanofibers was 169 to 1ppm H2 S at the same temperature.It is 57 times more than the sensitivity of Cu doped ZnO nanofibers,and 66 times more than the sensitivity of ZnO nanofibers.And the optimum working temperature of rGO/Cu doped Zn O composite gas sensing materials was significantly lower than that of ZnO nanofibers and rGO modified Cu doped ZnO nanofibers.It showed that the gas sensing properties were optimized to a greater extent by the electrospinning to composite rGO.3.A study on the gas sensing properties of the rGO and In doped ZnO composite nanofibers.The rGO modified In doped ZnO nanofibers were synthesized by hydrothermal method,and the rGO/In doped ZnO nanofibers were synthesized by electrospinning.By testing the surface morphology of SEM found that the doping of In changed the morphology of the nanofibers,and the nanorods with minor diameter was uniformly distributed on the surface of ZnO nanofibers.Gas sensitivity tests showed that the sensitivity of rGO/In doped ZnO nanofibers synthesised by electrospinning is 30 to 10 ppm NO at 200?.The best working temperature of rGO modified In doped ZnO nanofibers is 150?,and it was 50? lower than the working temperature of the In doped ZnO nanofibers.The sensitivity of rGO modified In doped ZnO nanofibers is 36 to 10 ppm NO at 150?.It is 30 times higher than the sensitivity of pure ZnO nanofibers.