Preparation Of Nanotube Graphene/metal Oxide Gas Sensors And Their Gas Sensing Properties

With the increasing environment pollution,the research on gas sensors has been attracted more and more attention.In this thesis,nanotube graphene(NTG)were grown by chemical vapor deposition(CVD)with nickel nanowires as substrates.N-type semiconductor materials by solvothermal method were combined with NTG,the three-dimensional structure of NTG has a large specific surface area and high adsorption performance,the p-n junction structure formed between the composite materials can improve the carrier transfer efficiency and further accelerate the gas-sensitive response to NO2 gas.Finally,the gas-sensitive response characteristics of the composite material to NO2 gas are studied.(1)By CVD,methane and hydrogen were cracked at high temperature,and graphene with uniform thickness was grown on the substrate of nickel nanowires grown by magnetic field-assisted chemical methodn-type semiconductor materials ZnO nanospheres with different growth conditions(growth temperature,growth time)were fabricated by solvothermal method,mixed with NTG to prepare composite materials with different mass ratios,and finally the composite materials were assembled on the interdigitated electrodes to make NTG/ZnO composite materials.The gas sensors show excellent response performance to NO2 gas as well as good repeatability and selectivity.The highest response of NTG/ZnO(mass ratio of NTG and ZnO is 1:2)composite gas sensors is 47.8%with a concentration of 50 ppm at 300 s of time,which is much higher than that of pure NTG gas sensors.At room temperature,the 300 s response to NO2 gas with a concentration of 100 ppb reaches 18.6%.The sensors can be recovered under the irradiation of ultraviolet light.In addition,the sensors show good repeatability and selectivity.(2)N-type semiconductor materials WO3 nanospheres were made by hydrothermal method.Mixing with NTG,composite gas sensors were fabricated.NTG/WO3(NTG and WO3 mass ratio of 1:3)composite gas sensors showed response of 43.8%at a NO2 gas concentration of 50 ppm at room temperature for 300 s.At room temperature,the 300 s response to NO2 gas with a concentration of 100 ppb reaches 17.1%.The sensors can be recovered under the irradiation of ultraviolet light.In addition,the sensor shows excellent repeatability and selectivity.Based on the three-dimensional NTG structure by CVD,two gas sensors,NTG/ZnO composite and NTG/WO3 composite,were fabricated.The composite sensors showed excellent response,repeatability and selectivity to NO2 gas at room temperature.