Graphite decoration with copper nanodots: Influence of graphite pre-treatment and copper particle synthesis route

Metal matrix composites have proven to be promising materials in which carbonaceous materials, such as graphite, carbon fiber, diamond, graphene, or carbon nanotube, have been introduced as reinforcements due to their intrinsic properties. The dispersion of the carbon materials, more specifically for nanoscale ones, still remains a challenge to this day. The functionalization of carbon reinforcements is a way to help their dispersion in a metal matrix. In this work, graphite decorated with copper (Cu) nanodots is fabricated through a liquid or solid route. The surface of graphite was pre-treated with nitric acid, phosphoric acid or an ester phosphate (CP213, dispersing agent) prior to nanodot deposition. Two fabrication routes were investigated: the solid route based on thermal treatments of dendritic copper particles and graphite under controlled atmosphere (air then hydrogen), and the liquid route based on Cu(II) precipitation in solution in the presence of graphite. These synthesis techniques enable the control of the interface through the growth of Cu nanoparticles that are chemically bonded to the graphite. Depending on the graphite surface pre-treatment and on the technique used, the size and the surface density of the Cu nanodots vary. Via the solid route, the size of the nanodots is between 20 and 300 nm whereas the liquid route leads to Cu nanodots with a size distribution between 50 and 150 nm.