Unexpected colloid-like supernatant from liquid-phase ball-milling graphite using miscible solutions as solvents: a failure analysis

Ball-milling graphite was conducted in miscible solutions with the purpose to exfoliate graphene. Colloid-like stable supernatants were unexpectedly obtained. Followed were the characterizations with Scanning electronic microscopy, Thermogravimetric analysis, X-ray diffraction and Elemental dispersive X-ray mapping to recognize them. As a result, strongly against the initial judgments, the components of colloid were mainly impurities of mixture of zirconia, silicate and yttrium oxide, other than nano-graphite.