A spontaneous combustion reaction for synthesizing Pt hollow capsules using colloidal carbon spheres as templates

Here we report a spontaneous combustion reaction in synthesizing Pt hollow capsules. In brief, Pt nanoparticles were loaded on the surface of colloidal carbon spheres by wet-chemical impregnation. When Pt-loaded carbon spheres were taken out of an argon-filled tube furnace at room temperature and exposed to air, they underwent spontaneous combustion. The internal carbon spheres templates were removed to leave nanostructured Pt hollow capsules. There are at least two critical conditions for the occurrence of the spontaneous combustion: the Pt particle size is below 5.8 nm, and the hydrogen content in the carbon spheres is above 2.570 wt %. Such a reaction is interesting for the preparation of metal hollow spheres and is also relevant with respect to removal of accumulated carbon on catalysts and for soot oxidation at room temperature.