Sperhydrophobic And Electrochemical And Self-cleaning Properties Of Graphene-based Composite Films By Plasma Enhanced Chemical Vapor Deposition

At present,fiber materials with superhydrophobic properties have many problems,such as severe reaction conditions,high self-toxicity of materials and difficult disposal of production waste,and the composite method of two-dimensional nano-graphite and fiber has become a research hotspot of multi-functional self-cleaning materials.In this paper,graphene-based composite films with superhydrophobic characteristic were deposited on fiber material using a plasma enhanced chemical vapor deposition(PECVD)technique,and the hydrogen bonding model of fluorine-doped graphene and fiber macromolecules was establised by the optimization of process parameters.The micro-nano structures and chemical compositions of graphene-based composite films were regulated,which was beneficial to improve the superhydrophobic and electrochemical properties of fiber materials.Furthermore,the structure of micro-nano battery was established by the introduced Zn atom,and the self-cleaning mechanism was revealed using a density functional theory(DFT)calculation,which provided an experimental basis for realizing the self-cleaning function of superhydrophobic fiber materials.The main research contents and conclusions are showed as follows:(1)The fluorine-doped graphene(FDG)films were deposited on the fiber surface using a PECVD technique,and the effects of discharge power on the microstructure,chemical compositions,superhydrophobic properties and electrochemical behaviors of obtained films were investigated.The nanostructures of FDG films were analyzed using a high resolution transmission electron microscope(HR-TEM),X-ray photoelectron spectroscopy(XPS)and fourier transform infrared spectrometer(FTIR),and the superhydrophobic and electrochemical corrosion mechanisms of FDG films were established by the combination of electrochemical impedance spectroscopy(EIS)and density functional theory(DFT)calculation.The results show that the FDG film deposited at the discharge power of 80 W with the rough surface presents excellent superhydrophobic and electrochemical properties,which are mainly attributed to the action of-CF2 functional group on the surface of FDG film.The arrangement of F atoms on both sides of graphene in the FDG film presents as the capacitor structure(C model)in the equivalent circuit model,and the F atoms prevent the electron transfer from the graphene surface,which is the mechanism of superhydrophobic property and electrochemical corrosion resistance of FDG film.(2)The micro-nano structure and chemical composition of graphene-based composite films were regulated by the change of gas type.The CF2-modified g-C3N4/graphene films were was deposited on the fiber material,and the microstructure,chemical compositions,superhydrophobic and electrochemical properties of obtained films were investigated.The results show that the g-C3N4 in situ grew on the graphene has the similar crystal structure as the graphene,and the introduced nitrogen atom increases the width of valence band for the graphene,which improves electrochemical corrosion property.The CF2-modified g-C3N4/graphene films exhibit amorphous structure,and the introduced fluorine atoms cause the serious deformation of g-C3N4 nanostructures,which creates electrostatic potential gaps on the graphene surface and provides the channel for electron transfer.In this case,their superhydrophobic and electrochemical properties are further improved.(3)The Zn-nano-particles(NPs)were in situ grew on the surface of graphene-based composite films by the chemical solvent method,which was used to construct the micro-nano battery structure.The nano-structure and self-cleaning properties of Zn composite films were analyzed using a TEM and XPS,and the self-cleaning mechanism was revealed by the DFT calculation.The results show that the Zn-NPs are well combined with the graphene(G),g-C3N4/graphene(NG)and CF2-modified g-C3N4/graphene(FNG)films.The NG@Zn-NPs and FNG@Zn-NPs films are reacted with the Zn(NO3)2 solution for 24 h,and the heavy metal ions are completely precipitated with the sediment of ZnO.The NG film and Zn-NPs form the complete micro-nano cell structure.The high electron flow contributed by the 2p orbital of N atom in the g-C3N4 reduces the conductivity;while the reactive oxygen[O]2-is decomposed by the g-3N4 reaction with the Zn2+ to form ZnO,which is the main factor for its self-cleaning properties.Moreover,the high-density charge distributed around the CF2 functional group on the FNG@Zn-NPs film also plays the superhydrophobic role.