Simple and green synthesis of high-quality macroscopic mesoporous carbon spheres facilitated by graphitic crystallite nanomaterials

Macroscopic mesoporous carbon spheres have many potential applications in separation, catalysis and energy storage. However, the synthesis of high-quality macroscopic carbon spheres remains challenging because carbonaceous gel spheres often suffer from a violently thermo-chemical conversion process in the carbonization and/or activation steps. Herein, we report a simple, efficient, environmentally friendly and scalable method to synthesize high-quality millimeter-sized mesoporous carbon spheres without the need for any surfactants, organic solvents and templates. For the synthesis of carbonaceous spheres, a mixed solution of a recently re-ported graphitic crystalline nanomaterials (GCNs), resorcinol (R) and formaldehyde was added dropwise into methyl silicone oil using a programmed heating process. The resultant carbonaceous spheres have an isotropic and homogeneous texture, and thus can withstand the drastic change triggered by the subsequent carbonization and steam activation steps at a high temperature. Consequently, the as-synthesized millimeter-sized mesoporous carbon spheres possess perfect shape, high strength and highly developed mesopores, depending on the GCNs dosage used. At a GCNs/R weight ratio of 1:4, the resultant millimeter-sized mesoporous spheres possess not only perfect shape and high hardness, but also a surface area of 1225 m2/g and mesopore volume of 1.3 cm3/g, which are predominantly distributed in the range of 5-25 nm. The adsorption results demonstrate that the as-synthesized millimeter-sized mesoporous carbon spheres exhibit excellent performance as blood purification materials.