Preparation Of Modified Graphene By Chemical Vapor Deposition And Its Metal Coating Properties

Since graphene was isolated in 2004,it has attracted extensive attention due to its novel structure and excellent performance.Its high quality impermeability,strong chemical inertness and other properties make it a good metal protective coating.When metals are exposed to corrosion environment for a short period of time,the graphene coating can provide a physical separation between the metal surface and the oxidative species such as O₂and H₂O,inhibiting corrosion of metals.But in long-term protection,O₂and H₂O come into contact with the metal from the graphene defects.Because of graphene’s extremely high electrical conductivity,galvanic corrosion would be formed between the metal and the graphene layer through electrons transport between the graphene layer and metal substrate.In this paper,modified graphene was successfully prepared by chemical vapor deposition.The obtained modified graphene reduces the conductivity of graphene,and inhibits the galvanic corrosion by cutting off the electron transmission on the interface,which can effectively enhance the long-term corrosion resistance of graphene.The specific research contents and results are shown as follows:（1）Modified graphene by nitrogen-doping（NG）and its properties of metal coatingNitrogen ions were pre-injected into copper foil by ion implantation.N-doped modified graphene（NG）was then prepared by chemical vapor deposition（CVD）on Cu substrate using copper acetate（Cu（OAc）₂）as carbon source.The structural characteristics of NG were characterized by scanning electron microscopy（SEM）,Raman and X-ray photoelectron spectroscopy（XPS）.The long-term protection performance of NG for Cu through environmental exposure corrosion test was characterized by optical microscope,polarization potential test and XPS.The results show that NG can significantly reduce the natural oxidation of Cu under long-term exposure to air,when compared with pure graphene（PG）.With the increase of N content,the long-term protection performance of NG coating will be better.The long-term protective mechanism of PG and NG coating on Cu was discussed.（2）Modified Graphene by Boron and Nitrogen Co-doping（BCN）and its properties of metal coatingModified Graphene by Boron and Nitrogen Co-doping was prepared on copper-alloyed strings by chemical vapor deposition（CVD）using trimethylboramane and copper acetate（Cu（OAc）₂）as the source of B,N and C,respectively.The structure of BCN was characterized by Raman and XPS.The long-term protection performance of BCN for copper-alloyed strings through environmental exposure corrosion test was evaluated by optical microscope,polarization potential test and XPS test.The results showed that BCN significantly reduced the natural oxidation of strings after long-term exposure,when compared to pure graphene（PG）coated on the surface of strings.The long-term protective mechanism of boron and nitrogen co-doped graphene coating on copper-alloyed strings was discussed.These findings reveal the corrosion mechanism of modified graphene-coated metals through combining its conductive properties of hetero-atom doped graphene.It can significantly improve its long-term metal protection characteristics and provide a potential way to improve the corrosion resistance of graphene as an effective barrier coating for metals.