Hydrothermal synthesis of microscaled Cu@C polyhedral composites and their sensitivity to convergent electron beams

Copper microparticles (2-5 um) encapsulated in carbonaceous shell polyhedral composites were mildly prepared via a one-pot hydrothermal process using copper nitrate, glucose, and sodium citrate at 150 degrees C, in which the glucose was found to play reducer and graphite source roles during the formation of these core-shell-like composites. Thermal stability results indicated that their weights remain almost unchanged below 240 degrees C in ambient atmosphere. It is interesting that the copper microparticles could be partially released out and translated into monodisperse Cu nanoparticles around the initial composites under the convergent electron beams in a transmission electron microscope (TEM). This phenomenon is an appealing discovery, which might endow the Cu@C composite with new functions; for example, it might be applied as a sensitive detector for the leakage of electron beams or other substances for the sake of being a safeguard. In addition, the corresponding hollow carbonaceous polyhedra were also obtained after the acid treatment, which might be used as a template to fabricate other kinds of polyhedra.