Figure 4: Kinetics of the synthesis of GO^Fe.

(a) XRD spectra of the samples taken from the synthesis process at the reaction times=0 min, 3 min, 5 min, 8 min, 11 min, 15 min 30 min, 45 min, 1 h and 2 h (1–10), respectively. (b) Interlayer spacing of selected samples at the OE stage versus reaction time. (c) TGA plots of the same samples as shown in a. (d) Weight loss of GO^Fe at 600 °C (left, red) and corresponding zeta potential (right, blue) as a function of reaction time. The kinetics of GO^Fe confirms that the whole reaction process completes in 1 h, including ~15 min of intercalation–oxidation and 45 min of oxidization–exfoliation. (e) Sample-H, Sample-T and GO^Fe (2 mg ml⁻¹) placed in water, indicating that only GO^Fe is well-soluble. (f) XRD spectra, (g) C1s XPS spectra and (h) TGA plots of GO^Fe, Sample-H and Sample-T with the reaction time 1 h. (i–k) SEM images of graphite, Sample-T and Sample-H, showing that the conventional Hummers methods with the oxidant of KMnO₄ can only result in thick graphite-like particles rather than slGO in 1 h of reaction time. Scale bar, 20 μm (i–k).