Fig. 3
From: Green synthesis of graphene oxide by seconds timescale water electrolytic oxidation
Investigation on the EC synthesis process of EGO. a-c, Step I: EC intercalation. Raman spectra (a), XRD patterns (b), and XPS C1s spectra (c) after intercalation for different time. From bottom to top in (a), the reaction time is 0, 1, 4, 10, 16, 17, 18, 20, 60, and 120 min in sequence. d-g, Step II: EC oxidation. d, Morphology and color change of a GICP slice with reaction time. Raman spectra (e), XRD patterns (f), and XPS C1s spectra (g) after reaction for different time. The Raman spectra and XRD patterns indicated by 0, 1, 2, and 3 min in (e) and (f) were taken from the as-synthesized GICP and EGO samples after 1, 2, and 3 min reaction, respectively, without cleaning and drying, and those indicated by 3 min, dry were taken from the samples obtained after 3 min reaction followed by cleaning and drying. It can be found that the contained water and H2SO4 have significant influences on the Raman spectra and XRD patterns (also see Supplementary Note 4 and Supplementary Fig. 9). The XPS C1s spectra in (g) were taken from the samples after cleaning and drying. h, C/O atomic ratio of the exfoliated product and the corresponding exfoliation rate of GICP in H2SO4 solutions with different concentrations. The error bar shows the range of C/O atomic ratio measured from five samples in each batch of product. i, Comparison of 18O content in the EGO samples synthesized by four different combinations of the normal and 18O-containing reagents, including H2SO4 for EC intercalation (normal Acid-Int/18O Acid-Int), and water (normal Aq-OX/18O Aq-OX) and H2SO4 (normal Acid-OX/18O Acid-OX) used in EC oxidation process. Normal: EGO synthesized with normal Acid-Int, Aq-OX, and Acid-OX; 18O Aq-OX: EGO synthesized with normal Acid-Int, 18O Aq-OX, and normal Acid-OX; 18O Acid-Int: EGO synthesized with 18O Acid-Int, normal Aq-OX, and normal Acid-OX; 18O Acid-OX: EGO synthesized with normal Acid-Int, normal Aq-OX, and 18O Acid-OX. (j), C/O atomic ratio of the exfoliated product and the corresponding exfoliation rate of FGP in H2SO4 solutions with different concentrations
