The C1s spectrum of GO can be deconvoluted into four peaks at 284

The C1s spectrum of GO can be deconvoluted into four peaks at 284.6, 286.7, 287.8, and 289 eV, corresponding to C=C/C-C in aromatic rings, C-O in alkoxyl and epoxyl, C=O in carbonyl, and O-C=O in carboxyl groups, respectively [30–33]. When GO is reduced, the peak intensity of C=C/C-C in aromatic rings rises dramatically, while those of C-O and C=O decrease sharply, and the peak of O-C=O disappears, clearly suggesting the efficient removal of oxygen-containing groups and the restoration of C=C/C-C structure in graphitic structure. It should also be noted that a new peak emerges at 291 eV corresponding to the π-π* shake-up satellite peak, indicating that the delocalized π conjugation

is restored [34, 35]. C/O molar ratios calculated according to the XPS analyses are 2.3 and 6.1 for GO and RGOA, respectively. FT-IR is also adopted to analyze the evolution of oxygen-containing groups during the self-assembly and reduction process (Figure 3b). As for GO, the following characteristic peaks are observed: O-H PF-04929113 price stretching vibrations (3,000 ~ 3,500 cm−1), C=O

stretching vibrations from carbonyl and carboxyl groups (approximately 1,720 cm−1), C=C stretching or skeletal vibrations from unoxidized graphitic domains (approximately 1,620 cm−1), O-H bending vibrations from hydroxyl groups (approximately 1,400 cm−1), C-O stretching vibration from epoxyl (approximately 1,226 cm−1), and alkoxyl (approximately 1,052 cm−1) [27, 36]. There is a dramatic decrease of GSK3326595 cost hydroxyl, C-O and C=O groups after the reduction process. A new SDHB featured peak at 1,568 cm−1 due to the skeletal vibration of graphene sheets appears. Combining the results of XPS and FT-IR analyses, partial oxygen-containing groups are still retained after the self-assembly and reduction process although there is a significant decrease of such functional groups. Figure 3 C1 s XPS spectra (a) and FT-IR spectra (b) of GO and RGOA. Electrochemical capacitive performances Three-electrode system Cyclic voltammograms of RGOA at

different scan rates in KOH and H2SO4 are shown in Figure 4a. The CV curves in both electrolytes show a rectangular-like shape, which is attributed to the electric double-layer capacitance in each potential window. As for the CV curves in KOH electrolyte, although there is no obvious redox peaks, RGOA also exhibits pseudocapacitance besides electric double-layer capacitance at the potential window of −1.0 ~ −0.3 V because the current density severely changes as the potential varies within this potential window [21]. An equilibrium redox reaction probably occurs as follows within this potential window [37]: contrast, there are obvious redox peaks within the potential window of 0.0 ~ 0.6 V in H2SO4 electrolyte, which are thought to be derived from the following redox reactions [38, 39]: Figure 4 Electrochemical performance of RGOA in KOH and H 2 SO 4 electrolytes.

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