Graphitized carbon with hierarchical mesoporous structure templated from colloidal silica particles

The mesoporous graphitized carbons were catalytically synthesized with the assistance of metal Ni by pyrolyzing polystyrene in the interstices of closed-packed silica spheres at 950 °C. By using colloidal silica with 10 nm, 36 nm in diameter or the mixed colloidal silica as templates, mesoporous graphitized carbon with monomodal or bimodal pore size distribution were prepared. The obtained carbons were characterized by the powder X-ray diffraction, N2 adsorption, Raman spectrometry, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray analysis and thermogravimetic analysis. It was found the presence of nanometer Ni in the silica template was crucial to the graphitization of the final mesoporous carbon. HRTEM revealed that the graphene layers were curved and seemed to be densely stacked parallel to the external surface of the silica spheres. The specific surface area and total pore volume of the resulting graphitized carbon were highly dependent on the proportion of two type of colloidal silica with different particle size (10 and 36 nm, respectively). The experimental surface area and total pore volume were compared with theoretical value by supposing that the mesopores created by spherical silica could form cubic closed-packed structure. The difference between experimental and theoretical value was analyzed.