Preparation And Gas Sensing Properties Of Graphene Oxide Based Composite Gas Sensing Materials

With the rapid development of social science and technology and the entry of artificial intelligence into life,the perception ability of materials has become an important part of the demand of contemporary science and technology development,and gas concentration sensor,as an important branch of it,has gradually entered the field of intelligent factory.As the representative of high specific surface area and high electron transfer efficiency,graphene oxide?go?can effectively improve the gas selectivity and sensitivity of the sensor in theory.Graphene oxide with two-dimensional plane structure will make most of the carbon atoms on the surface exposed in the air,which provides a large specific surface area for gas adsorption.The high electron mobility of graphene oxide makes it easy to change the resistance once the gas is adsorbed on the surface,which makes it possible for graphene oxide to become an excellent gas sensing material.In order to explore the practical role of graphene oxide materials in sensors,this paper aims to use titanium dioxide nanotubes?TiO₂NT?and tin dioxide/nickel oxide?SnO₂/NiO?as the main body of the composite,and use p-n heterojunction and chemical bond to load on the substrate go to prepare the composite.By means of SEM,TEM,XRD,EDS,XPS,sensitivity,response time,working temperature and repeatability of gas sensors,the introduction of go into the composite structure of p-n junction and chemical bond is illustrated from two aspects And the organic functional groups on the surface of go can improve the selectivity of gas sensing materials.The gas sensing test of the two structures is of great significance for the future study of go in gas sensing materials.The specific research is as follows:GO was prepared by modified Hummer method,nano-TiO₂ was prepared at different calcination temperatures,and nanotube-shaped TiO₂was selected as the substrate of the composite material to obtain p-n heterojunction composite material GO/TiO₂NT.The SEM test results show that TiO₂NT is flat on the surface of GO and forms a physical heterostructure.The results of X-ray diffraction show that anatase titanium dioxide is successfully prepared and there is no impurity peak.Then the gas sensing properties of GO/TiO₂NT composite were measured.The results showed that the best working temperature of GO/TiO₂NT composite was250?,and it had good gas sensing properties to acetone with concentration of 0.3-10 ppm.It could effectively identify the acetone concentration in the environment.In the same concentration of 10 ppm formaldehyde,methanol,ammonia,toluene and ethanol,the sensitivity of GO/TiO₂NT composite to acetone was higher than that of other gases The increase of sensitivity is attributed to the bending space charge region formed by the relative movement of electrons in the p-n junction,which makes the GO/TiO₂NT composite have lower resistance and higher sensitivity than TiO₂NT in acetone environment.SnO₂/NiO was prepared by coprecipitation method.After calcined at400?for 2 hours,a binary composite with good crystallinity was obtained.Then GO/SnO₂/NiO Composite was prepared by hydrothermal method,in which go was used as the substrate and SnO₂/NiO was secondary grown on the surface of GO.XRD results show that SnO₂/NiO has good crystallinity,and XPS results prove the existence of Sn-O-C.This is because of the chemical bond structure between GO and SnO₂/NiO.Finally,the successfully prepared GO/SnO₂/NiO composite material was coated on the surface of the gold electrode for gas-sensing test.It was found that the temperature range of 350?has a good response to acetone with a concentration range of 10 to 500ppm,compared with the composite The response time,recovery time and sensitivity of SnO₂/NiO and GO/SnO₂/NiO have been significantly improved.When the temperature is 350?,the sensitivity to 50ppm acetone is 21.11,the response time is only 5s,and the recovery time is 150s.After repeated testing for one month?6 times?in a row,the response of GO/SnO₂/NiO composites can still maintain sensitivity above 95%,and the sensitivity maintains a good linear relationship with different concentrations of acetone,indicating that gas-sensitive materials The gas sensing performance is very stable.These two structural designs are a new idea for the application of graphene oxide in sensors,and the article also provides a tentative explanation of the gas sensing mechanism,which can effectively connect the experimental data through theory.This is the future of graphene oxide.The research of sensor application opens a new research direction.