Study The Synthesis And Gas Responsivity Of Polychromatic Graphene Thin Film

In this paper,a modified Hummers'method was used to synthesize graphene oxide?GO?,and the thickness controlled polychromatic GO film was prepared by dip-coating method.The response of polychromatic GO film to EtOH was successfully realized.We used amino azobenzene?Azo?to modify GO,the contact angle of GO-Azo film prepared is 152°,and the super hydrophobic GO-Azo film material is successfully prepared,which is expected to realize the visual detection of aromatic gases.In the first chapter,firstly,we summarize the excellent properties and application value of graphene materials in optics,electricity and mechanics.Next,the types of graphene materials and the methods of preparing graphene based films are introduced,and the advantages and disadvantages of several commonly used methods are also presented.Then,the research background and research status of graphene based gas sensors are introduced.It is pointed out that most of the electrical sensors are weak in anti electromagnetic interference and poor selectivity.We introduced a new type of graphene based optical gas sensor and explored its response mechanism.Finally,the purpose,significance,content and innovation of this research are presented.In the second chapter,a series of GO thin films for colorimetric sensing was fabricated by dip-coating technique.These films exhibited ultrafast response,good reversibility and obvious optical shifts within the visible range toward ethanol.Fourier transform infrared spectroscopy?FTIR?spectra confirmed that GO was successfully synthesized.Scanning electron microscope?SEM?and atomic force microscope?AFM?showed that the thickness of GO film can be modulated within 200 nm to 275 nm.Ultraviolet-visible?UV-vis?spectrophotometer demonstrated that the spectra red shift with the increase of thickness of GO film.Dynamic study showed that absorption and desorption time was 120 ms and 80 ms,respectively.The selectivity of the GO sensor was studied by measuring the response time towards four kinds of vapor including EtOH,MeOH,H₂O and NH₃.The response time of EtOH was 120 ms and detection limit was 3.33 ppm.Colorimetric properties of GO film showed a promising application for fast and visualized sensing of ethanol with high performance.In the third chapter,Azo compound is used to modify the surface of GO,and GO-Azo hybrid material is synthesised through a covalent grafting of amide linkage.The formation of GO-Azo hybrid material was confirmed by FTIR and UV-vis spectra.The contact angle of the material is 152°,which proves the successful preparation of super hydrophobic GO-Azo hybrid material.In the fourth chapter,we summarized the conclustions and innovation of this project.In this paper,the polychromatic GO film is prepared by the dip-coating method.Based on the thin-film interference principle,the detection of VOC gas is visualized,which is of great significance for the future development of the GO optical gas sensor.