Co-assembly strategy for uniform and tunable hollow carbon spheres with supercapacitor application.

Carbon materials with hollow structure have wide applications in adsorption, electrochemistry, catalysis and many other fields. Herein, hollow carbon spheres (HCS) with uniform spherical morphology, adjustable structure, and abundant mesopores are prepared by a feasible co-assembly of hexadecyl-trimethyl-ammonium-bromide, silica precursor (teraethoxysilane (TEOS)) and carbon precursor oligomer (phenol/formaldehyde (PF) resin) in a Stöber-like system. Alcohol-water based solvent of the reactant system shows strong effects on the hydrolysis rate of TEOS relative to the polymerization rate of PF resin, which results in tunable structures for HCS materials. With the increase of alcohol-water ratio, the structure of HCS can be adjusted from irregular porous particles to hollow spheres, and then to core-shell structure. In addition, the diameter of the core increased and thickness of carbon shell decreased for the HCS. The obtained HCS showed rich mesoporous structure, thin carbon shell and relative uniform spherical morphology, which endow HCS with good electrochemical performance for supercapacitor, indicating their promising ability in energy storage.