Study Of Quartz Crystal Microbalance Gas Sensor Based On Graphene Composite Film

Graphene has many excellent properties in several aspects such as electrical conductivity,mechanical properties,electron transport capacity,specific surface area and so on,so graphene is suitable for using in gas sensor field as sensitive material.However,the pure graphene with high specific surface area usually has poor selectivity to different kind of gases.Consequently,in this paper,the advantages of graphene and organic polymer materials are combined together,and finally we prepared the quartz crystal microbalance gas sensor which is based on graphene/organic polymer composite film.The work starts from gas sensitive mechanism.Firstly,various types of graphene materials are characterized and their influences to gas sensing are also discussed.Besides,the characteristics that organic polymer compound should possess are discussed.At last,we choose polyvinylpyrrolidone(PVP)and polyacrylic acid(PAA)to combined with graphene oxide(GO)to make the composite film,and finally prepared two kinds of QCM gas sensors based on PVP/GO and PAA/GO composite film.The gas sensing mechanism,film characterization and gas sensing properties of these two kinds of sensor are studied.As for the study of graphene/organic polymer composite thin film device,firstly,FTIR,UV,Raman spectroscopy,SEM and BET are used to characterize and analysis the PVP/GO composite film.The result revealed that by adding GO to PVP,the composite film has bigger specific surface area which provide more sites for gas adsorption and accordingly enhanced the sensing response.Then,by changing different concentration ratio and other factors in film preparation,we explored the best parameter in preparation process.The experimental results showed that the PVP/GO composite film QCM gas sensor based on best parameters has high sensitivity,good reproducibility compared to pure PVP film sensor,and shows good selectivity for ammonia,but its long-term stability need further improve.Then,the PAA/GO composite film based device is prepared and characterized by FTIR,UV and SEM characterization.The influences in film morphology and other aspects by adding GO are analyzed.After that,the best preparation parameter of PAA/GO composite film is explored as well.Finally,the gas sensing performance of this device is tested,the results showed that the sensitivity of gas sensor based on PAA/GO composite is much higher than pure PAA film,and this device also owns high reproducibility,perfect linearity and high selectivity to ammonia.What's more,its long-term stability has a good improvement compared to PVP/GO composite film device.In general,the two types of QCM gas sensors based on PVP/GO and PAA/GO composite film have good gas sensing property,and they are suitable to detect ammonia at room temperature.