▎ 摘　　要

The non-oxidation-based procedure is proposed for the production of high-quality graphene nanosheets using graphite as the raw materials. This research demonstrated a hybrid two-step production method by liquid-phase exfoliation (LPE) of Premilled graphite in Dimethylformamide (DMF) and compared it with the purely milled and just sonicated samples. However, a simple physical separation procedure composed of two centrifuge processes also designed for the separation of the products in each step. By this process, the exfoliated graphite, less-exfoliated ones and produced nanoparticles are separated, and the less-exfoliated ones are reused again in moderate sonication process. Two grades of graphene nanosheets and a grade of graphitic nanoparticles result at the end. The quality and the nature of defects in all graphene samples produced from LPE, wet milling of graphite and a combination of both, was investigated and discussed by Raman spectroscopy related indices. Raman spectra analysis indicates the adverse effect of sonication power on the in-plane defects formation in the graphene nanosheets which could be hindered by the reduction in power of sonication along with the pre-milling of the graphite. Also inductively-coupled plasma (ICP) and field emission scanning electron microscopy (FE-SEM) analysis used for further characterization of the milled-sonicated sample.