  Copper (Cu) is the electrical conductor of choice in many categories of
electrical wiring, with household and building installations being the major
market of this metal. This work demonstrates the coating of Cu wires - with
diameters relevant for low voltage (LV) applications - with graphene. The
chemical vapor deposition (CVD) coating process is rapid, safe, scalable and
industrially compatible. Graphene-coated Cu wires display oxidation resistance
and increased electrical conductivity (up to 1% immediately after coating and
up to 3% after 24 months), allowing for wire diameter reduction and thus
significant savings in wire production costs. Combined spectroscopic and
diffraction analysis indicate that the conductivity increase is due to a change
in Cu crystallinity, induced by the coating process conditions, while
electrical testing of aged wires shows that graphene plays a major role in
maintaining improved electrical performances over long periods of time.
Finally, graphene coating of Cu wires using an ambient pressure roll-to-roll
(R2R) CVD reactor is demonstrated. This enables the in-line production of
graphene-coated metallic wires as required for industrial scale-up.
