| Graphene, a new nanao material with special structure and properties. Due to unique mechanical,charge carriers, transmittance,thermal conductivity, graphene has expansive application prospect in transparent conductive film, lithium ion battery, supercapacitor, functional composite. Mechanical exfoliation,reduction of graphene oxide,chemical vapor deposition,epitaxial growth are the preparation method of graphene. Chemical vapor deposition is one of important method acquire large area and high quality graphene films. In this paper, we raise CVD synthesis of graphene using alcohol at low hydrogen concentration and atmospheric pressure(E-APCVD) with a view to safety and economy.This research content mainly includes:(1) Focus in safety and economy, craft process and technological parameter have be confirm by discuss the technological conditions.Firstly, equipment has been refitted in order to according with experiment requirements. Graphene films with varying thickness can be synthesized by controlling parameter. Raman, scanning electron microscopy(SEM) and transimission electron microscopy(TEM) are developed to characterize the quilaty, morphology, structure of graphene. At last, experiments were desgined to analysis the mechanism.(2) The parameter and process of chemical etching method has been confirmed for transfer graphene film.Electrochemical delamination is used to transfer few-layer graphene on nickel by the first time.Based on long-term experiments, we raise a method named self-standing to transfer graphene which has been used to prepare graphene/Au and optical filter protective film of soft X-ray laser.(3)The preparation process of graphene/Au confirmed based on self-standing method. SEM image of graphene/Au which used to analysis quality and structure obtain from sample preparation with different mode.(4) We discuss the influencing factor and formulate craft process of graphene laser mode-locking device on account of graphene saturable absorber. The performance of those devices has been analysised by mode locking test.The following conclusions may be from the results presented above:(1)Varying thickness, high quality, large area graphene films can be synthesized by E-APCVD successfully.(2)The carbon atom originate from dissociation of ethanol expand to high-activity Cu which play a role like catalyst after preheating. Those atom nucleation and growth on the high-activity location after sdsorb on Cu. The initial grain keep growing from island domain to dendritic flake. Graphene can go across the grain boundary of Cu until form perfectly film.(3) Chemical etching method is the proven techniqueto transfer graphene.The technological parameter of spin ploymethyl methacrylate(PMMA): 4wt%PMMA/anisole, initial rotate speed 1000 r.p.m., 60 s. Final rotate speed 2000 r.p.m., 120 s; Electrochemical delamination successfully apply to transfer few-layer graphene on nickel. The time of the electrochemical exfoliation has direct ratio relation with current.The graphene/PMMA easily to be teared by an excess of bubbles when the current is over 0.1A. Self-standing is one of handy method which can be used to preparate optical filter protective film of soft X-ray laser and graphene laser mode-locking device.(4)Graphene/Au interlayer material with well-storied structure successfully synthesized by layer-by-layer assembly which blaze away in simplify preparation of graphene/metal.(5)Laser mode-locking device can be synthesized with graphene as function units. The cleanliness of graphene on optical has direct influence on laser pulse, not the drape stem from dring process. |
PDF Full Text Request