The Differences of Graphene Oxide Products Made from Three Kinds of Flake Graphites.

Graphene oxide (GO), a widespread load platform in many research studies based on its microstructures, is largely made from flake graphite by a strong oxidation method. However, the differences of GO products made from different flake graphites have received little attention. Here, five GO products made from five different flake graphites by the Hummers method are investigated. The results reveal the differences in microstructures of the five GOs concerned with the ratio of C-C sp2 structures to defects and the amount of oxygen-containing functional groups, which are further evidenced by their performances of quenching efficiencies by five DNA fluorescent probes. We demonstrated that the microstructural differences of GO products are transmitted from their parent flake graphites. Meanwhile, three kinds of parent flake graphites are proposed: (1) with large flakes and complete C-C sp2 structures, (2) with large flakes but defective C-C sp2 structures, and (3) with fine flakes but moderate C-C sp2 structures, in which the performance of GO made from (1) is the best while the GO made from (3) shows comparable to or even better performance than that made from (2). Our work gives a reminder for precisely choosing graphite in the preparation of GOs and the potential value of tremendous natural fine-flake graphites.