The Study Of Effect Of Different Graphene Layers And Crystal Faces Of Polycrystalline Copper On Copper Corrosion

Graphene has unique spatial structure and strong covalent bond between atoms and other factors determine that it has distinct differences from the general twodimensional materials characteristics.In addition,the flawless graphene also has excellent shielding properties,which can effectively shield oxygen,water molecules and other corrosion factors reach the metal surface.Consequently,it has been considered as the thinnest corrosion protection coating so far.In this paper,the mechanisms of promoting or suppressing corrosion of different layers of graphene coated copper under atmospheric conditions were studied.Though CVD graphene has a protective effect at high temperatures,it has been found that different numbers of graphene in long-term storage under atmospheric conditions has significantly different effects on the corrosion of polycrystalline copper substrates.Optical images and Raman spectra show that single layer graphene(SLG)coated copper foil has a higher degree of corrosion than bare copper(without graphene coating)on the same sheet of copper foil.In addition,the differences in chemical activity shows a significant distinction in the degree of corrosion of both the <001>//ND and <111>//ND oriented graphene-coated copper grains.However,when CVD situ-grown bilayer graphene(BLG)covered,the copper foil is effectively prevented from being etched to exhibit a bright yellow color despite the different crystal face types.The surface potential difference measured by EFM shows that a contact potential difference(VCPD)between 30 and 40 mV exists between the Cu/SLG and the bare copper.The SLG coating makes the work function of the copper surface smaller and more prone to loss of electron reaction to form galvanic corrosion.The BLG coating makes the copper surface potential becomes lower,the work function becomes larger,so BLG successfully protect the copper from being corrosive.These findings have a foreseeable significance for graphene as a metal anti-corrosion coating.