Controllable synthesis and modification of carbon micro-spheres from deoiled asphalt

A series of size-controllable carbon micro-spheres (CMSs) were synthesized from deoiled asphalt by chemical vapour deposition, with the emphasis on the effect of reaction temperature, Ar flow rate and collection zone. Graphitized carbon micro-spheres (GCMSs) were obtained from as-prepared CMSs by vacuum heat treatment at 2000 °C for 1 h. Air oxidation was performed to realize functionalization of CMSs. Morphologies and structures of CMSs and GCMSs were characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Raman spectroscopy, and the functional groups on the surface of GCMSs and CMSs were characterized by Fourier transformation infra-red spectrometry. Results show that effective mass production of size-controllable CMSs, with diameters ranging from 100 nm to 1 μm, was achieved. As-obtained high purity CMSs were spherical with uniform size and low graphitization degree, but the graphitization degree of GCMSs was enhanced obviously. By air oxidation, some oxygen-containing functional groups were introduced onto the surface of CMSs, while no functional groups were introduced onto the surface of GCMSs.