Preparation And Gas Sensing Properties Of RGO/SnO₂ Composite Nanofibers

In recent years,with the rapid development of economy,energy,transportation,medical treatment and other fields,environmental problems have gradually occured.Acid rain,haze and gas leakage often occurs.Take H₂S gas for example,one of the main components of acid rain,which is produced in daily activities such as sewage treatment and landfill,but it is not easy to be detected at low concentrations.Semiconductor metal oxide?MOS?gas sensors such as SnO₂ have attracted much attention due to their high sensitivity,fast response,simple preparation,low cost and other advantages.However,high operating temperature and poor selectivity also limit the practical application of MOS gas sensors.In addition,graphene and its derivatives,such as reduced graphene oxide?rGO?,have been reported to show good sensing properties.In this paper,SnO₂ will take as the research object and improve the gas sensitivity of SnO₂ materials through rGO composite and metal element doping.The main research contents are as follows:1.rGO/SnO₂ composite nanofibers were prepared by electrospinnig and the structure,morphology,gas sensing properties of nanofibers were studied by scanning electron microscope?SEM?,transmission electron microscope?TEM?,X-ray diffraction?XRD?and Raman spectrometer.The results showed that the rGO composite had no significant impact on the crystal structure and morphology of the SnO₂ material.Gas sensitivity test results show that different rGO compounds can improve the sensitivity of the material to target gas H₂S.When the rGO compound amount is 0.5 wt%,the composite material has higher gas sensitivity to H₂S,and the sensitivity to 5 ppm H₂S gas at 100?can reach 80,and the selectivity is also significantly improved.2.Transition metal elements?Cu,Ni?were used to dope rGO/SnO₂ nanofibers,and the influences of doping elements and doping amount on the microstructure and gas sensing properties of rGO/SnO₂ nanofibers were studied.The test results showed that small amount of Cu and Ni doping had no significant effect on the microstructure and crystal structure of the composite nanofibers.The gas sensitivity test found that when the Cu doping amount was 1 at%,the composite material had the best response to H₂S.When the working temperature was 100?,the composite material's sensitivity to 5 ppm H₂S gas was as high as 17358.Meanwhile,the composite material's response recovery ability,selectivity and stability were improved too.The Ni doping amount was 1 at%,and the sensitivity of 1 at%Ni doped SnO₂ composite to 5 ppm H₂S was 3496 at room temperature,with high sensitivity,low detection limit?0.01 PPM?and excellent selectivity.3.The doping of rGO/SnO₂ composite nanofibers was studied with rare earth elements?Ce,La?.The influences of doped elements and doping amount on the microstructure and gas-sensitive properties of rGO/SnO₂ nanofibers were studied.The gas sensitivity test of Ce doped composites shows that Ce doping can improve the gas sensitivity of rGO/SnO₂ composite nanofibers to H₂S.The optimal doping amount of Ce is 3 at%,and the response value to 5 ppm H₂S gas at 75?can reach300,with high selectivity and low detection limit.La doped composite gas-sensing performance tests show that the right amount of La doping rGO/SnO₂ composite nanofibers can realize the room temperature detection of H₂S gas sensor.The best doping amount is 2 at%La and the sensitivity to 5 ppm H₂S can reach 256000 at room temperature.The response of the composite material has excellent response-recovery times,high selectivity and low detection limit?0.005 ppm?.