Direct synthesis of high-quality graphene on Cu powders from adsorption of small aromatic hydrocarbons: A route to high strength and electrical conductivity for graphene/Cu composite

A low-cost and easily-accessible approach based on adsorption of small aromatic hydrocarbons (SAHs) was developed to synthesize graphene on Cu powders, which could supply raw material for powder metallurgy (PM) fabrication of graphene/Cu composites. Two common SAHs, naphthalene and α-naphthol, were chosen as the carbon precursors. Compared with naphthalene, it was found that the hydroxyl group in α-naphthol could be chemically adsorbed on Cu powders, which could not only be effective in preventing Cu powders from agglomerating together at high temperature but also promote the growth of high-quality graphene. Therefore, α-naphthol-derived graphene on Cu powders were chosen to fabricate graphene/Cu composites by spark plasma sintering and hot-rolling. The composites exhibited a microstructure with extremely homogeneous dispersion of graphene, exceptional high strength and simultaneously similar electrical conductivity compared with that of the matrix. Cu–O–C bond was found and could improve the interfacial bonding between graphene and matrix. Experimental and theoretical calculation results revealed that the load transfer, grain refinement and thermal mismatch mechanism provided by graphene were the main strengthening mechanism in the composite. This synthetic procedure is quite scalable for industrial use to fabricate graphene/Cu composites with high performance.