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Concomitant Thionation and Reduction of Graphene Oxide Through
Solid/Gas Metathetical Sulfidation Reactions at High Temperatures
Ki-Wan Jeon and Dong-Kyun Seo*
Department of Chemistry and Biochemistry, Arizona State University
Tempe, AZ 85287-1604, USA
Email: dseo@asu.edu
Supplemental Materials
Figure S 1. Raman spectra of (a) graphite flake, (b) GO, (c) ttGO, and (d) RGOS. The G bands
appear around 1600 cm-1, while the D bands are visible around 1340 cm-1 for all the samples
except the graphite flake. Graphite flake exhibits a 2D band at 2712 cm-1.1 The positions of the
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G band for GO, ttGO, and RGOS are higher in frequency than that for graphite flake, which has
been attributed to significant defects on graphene sheet.1a, 2 The Full Widths at Half Maximum
(FWHMs) of the G band of GO, ttGO, and RGOS are much larger than that of graphite flake,
which is due to a higher degree of atomic disorder.1b, 3 The ID/IG ratio of RGOS (1.11) is almost
the same as that of GO (1.08).
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Figure S 2. XPS survey scans of air-dried GO (left) and RGOS (right). See the main text for the
details.
Figure S 3. Representative SEM image and EDS spectrum of air-dried RGOS. See the main text
for the details.
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Figure S 4. ATR FT-IR spectra for ethanol (black line) and GO solution dispersed in ethanol
(blue line) and RGOS dispersed in ethanol (red line). The RGOS dispersion shows two weak
peaks at 617 and 717 cm-1 which are attributed by C–S stretching vibration.4 The C–S stretching
vibration is known to have a low intensity.5
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Figure S 5. UV-Vis spectra of L-cysteine standard solutions with various concentrations and a
mixture of RGOS and DTNB in aqueous Tris-HCl buffer at pH 8 in the Ellman assay
experiment.6
Figure S 6. Plot of optical absorbance at 413 nm versus thiol concentration obtained from
Figure S 5. Black dots and white dot represent the standard solutions and a sample solution,
respectively. The straight line (red) is a linear least square fit of the experimental data (Rp =
0.998).
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Figure S 7. XPS survey scan (top-left) and high-resolution XPS spectra of core level region of
C1s (top-right), O1s (bottom-left), and S2p (bottom-right) of RGOS after heat treatment at 600
°C.
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Figure S 8. UV-Vis absorption spectra of GO (black) and RGOS dispersions (red). The red-shit
of the peak maximum is consistent with the reduced nature of the graphene sheets.7, 8
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