Study On Preparation And Gas Sensitivity Of Nickel Oxide Materials

In today's society where the industry is extremely developed,the waste gases expelled from production and living is very harmful to the environment and human health.The detection and control of these harmful gases have always been the focus of people's attention.Semiconductor metal oxide gas sensors have become one of the research hotspots of gas sensor,which is used to detect the types and concentrations of these toxic gases.Nickel oxide is a P-type semiconductor with a band gap of 3.6-4.0 eV at room temperature.Because nickel oxide has the advantages of simple preparation,low cost and good stability,it is widely used in the direction of gas sensors.In this paper,nickel oxide is used as the main research material,and the synthesized material was characterized and analyzed by scanning electron microscopy(SEM),thermogravimetric analyzer(TG),X-ray diffraction(XRD)and energy disperse spectroscopy(EDS).Nickel oxide and its doping materials were prepared by simple hydrothermal method,and gas-sensitive performance tests were performed on a gas based on these prepared materials.The test results show that the gas sensor has better gas sensitivity.The main research contents are as follows:(1)In this paper,nickel oxide microflowers were prepared by hydrothermal method and high temperature calcination with nickel nitrate hexahydrate as nickel source.And the gas-sensitive performance of the gas sensor based on nickel oxide microflowers were tested.The gas sensitivity test results show that the gas sensor has good gas sensing performance to ethanol gas.When the operating temperature is 164 ?,the sensitivity of the sensor to 100 ppm ethanol gas is 3.10,and the response and recovery time are 13 s and 27 s,respectively.The gas sensor has a minimum detection concentration of 50 ppm for ethanol and a sensitivity of 1.89.At a certain relative humidity(33%,58%,75%,97%),the gas sensor has little effect on detecting ethanol detection.(2)In order to study the effect of a small amount of other metal elements doped on the gas sensing properties nickel oxide,a one-step hydrothermal method was used to dope Fe elements into nickel oxide microflowers,and sheet-shaped Fe-NiO materials was prepared.The gas sensing performance of the gas sensor constructed based on this material was tested.The test results show that the doping of a small amount of Fe element changes the dominant gas detected by the pure nickel oxide gas sensor and reduces the optimal operating temperature of the sensor.The Fe-NiO sensor is more sensitive to formaldehyde.Its sensitivity to 100 ppm formaldehyde at 144 ? is 3.43,and its response and recovery time are 17 s and 18 s,respectively.The gas sensor has a minimum detection concentration of 20 ppm for formaldehyde and a sensitivity of 2.19.(3)A small amount of Sn doped nickel oxide prepared sheet-shaped Sn-NiO materials by one-step hydrothermal method,and the gas sensor based on this material was tested.The test results show that the Sn-NiO gas sensor exhibits good gas sensitivity to methanol.When the operating temperature is 144 ?,the sensor has a sensitivity of 5.23 to 100 ppm methanol,and its response and recovery time are 13 s and 29 s.The gas sensor has a minimum detection concentration of 20 ppm for methanol and a sensitivity of 2.25.