https://phys.org/news/2018-05-newly-copper-graphite-combo-efficient.html

The scientists bombarded graphite in an ultra-high vacuum environment with ions to create surface defects. Copper was then deposited on the ion-bombarded graphite while holding it at elevated temperature, at 600-800 K. The synthetic route created multilayer copper islands that are completely covered by graphene layer(s).

"Copper is a highly conductive material but susceptible to oxidation. Being able to successfully embed it just underneath the surface of graphite protects the copper, and suggests a number of potential applications, including battery technology," said Research Assistant Ann Lii-Rosales.