Scalable manufacturing of hierarchical nanostructures for thermal management

Thermal oxidation of copper is a simple and scalable method to produce copper oxide nanowires. We report for the first time the formation of nanowires on copper powder during thermal oxidation and the resulting nanowire coverage that is dependent on initial particle size. Systematic thermogravimetric analysis (TGA) and in-situ x-ray diffraction (XRD) studies of thermal oxidation of particles of different sizes provide insights into the size-dependent process and evolution of the various phases of copper and copper oxide with time. Furthermore, we find that a large void is formed within these particles after oxidation and propose a mechanism based on the Kirkendall effect. Using this new size-dependent oxidation process, we demonstrate the simple and scalable creation of new hierarchical structures for applications in thermal management, including electronics cooling and boiling.