Low-temperature solution synthesis of carbon nanoparticles, onions and nanoropes by the assembly of aromatic molecules

Graphitic carbon nanostructures were prepared in solution by two methods: solvothermal synthesis and hot injection. Small carbon nanoparticles with uniform diameters of 3–6 nm, carbon onion particles with larger diameters of 30–80 nm, and carbon nanoropes with a length of hundreds of nm and a width of 3–20 nm, were formed using commercial mesophase pitches as a carbon precursor through solution-phase synthesis below 200 °C. In the solvothermal synthesis, organic–organic assemblies of aromatic molecules from the pitches could be constrained into different stacking arrangements directed by varying the concentration of the block copolymer P123 template in toluene solution at 200 °C. In the hot injection method, when oleic acid was used as a solvent at 180 °C, the assemblies of the aromatic building blocks were controlled by varying the reaction time (5–30 min) or the concentration of H2SO4 catalyst (0.015–0.061 mol L−1) in the nucleation and growth process.