Insights into the effect of graphene on Cu electrical conductivity: Experimental investigations of Cu foil coated with graphene

Cu foil is one of the key engineering materials with extensive applications in microelectronics and energy storage systems, with high electrical conductivity being crucial to device performance and energy efficiency. Graphene (Gr) is a promising material to enhance Cu conductivity due to its extraordinarily high carrier mobility, but the experimental results on Cu/Gr composites are controversial, and the fundamental mechanism is not yet clear by experiments. In this work, we prepare a unit experimental model system, which is a 25 μm thick Cu foil with atomic layer graphene grown on the surface. Characterization analysis shows that the Cu/Gr interface is the physisorption type without chemical bonding formed. Impressively, the angstrom thick graphene layer increases the conductivity of micrometer thick Cu foil by 2.8% IACS (International annealed Cu standard, 5.80 × 107 S m−1), displaying an enormously high volumetric enhancement effect. The Hall effect measurements disclose that the graphene layer yields a light reduction of carrier concentration but a more pronounced increase in carrier mobility. In addition, in situ electrical measurements under uniaxial tensile strain show that the graphene layer keeps the strained foil with constantly lower electrical resistance than pristine Cu foil until failure. The present work provides insights into the mechanism for graphene's effect on Cu conductivity, and the model system demonstrated is viable for a wide variety of metallic foil systems, where high electrical conductivity is needed.