Fig. 2: Characterization of nominal graphene materials (NGM).
From: Cytotoxicity survey of commercial graphene materials from worldwide

Three-dimensional plots of the physiochemical properties defining the quality of graphene according to Wick et al., with a ΔTG. b r(sp2); and c wt%(C). d 3-Dimensioal plot comparing all three before-named measures for the degree of functionalization. A blue bar or blue circle indicates the direction of “ideal” graphene: The more the points are located at this axis or point, respectively, the more ideal the structure31.