Mechanochemical synthesis of porous carbon at room temperature with a highly ordered sp² microstructure

Carbon nanostructures with a well-developed turbostratic sp² structure and high porosity are synthesized at room temperature inside a planetary ball mill. The obtained carbons were analyzed in-depth by means of gas adsorption, wide-angle X-ray scattering (WAXS), Raman spectroscopy, and transmission electron microscopy (TEM). Our approach involves the solvent-free reaction between calcium carbide (CaC₂) and hexachlorobenzene (C₆Cl₆) conducted under mechanochemical conditions. After certain mechanical activation time, the exothermic nature of the reaction (−492 kcal) provokes a combustion-like event that results in innocuous salt (CaCl₂) and a carbonaceous material. Carbon with a high degree of structural order in the constituting graphene and the graphene stacks, possessing almost no internal surface, can be obtained after 5 min of milling time with a mass ratio CaC₂/C₆Cl₆ of 0.9, while carbon exhibiting a surface area as high as 915 m²/g can be obtained after 2 h of milling time with a mass ratio CaC₂/C₆Cl₆ of 5.1. WAXS results and TEM observations reveal a mixture of amorphous carbon and non-graphitic phases. Among the last one, spherical-shaped carbons and curved nanosized strips can be easily distinguished.