  The structure of graphite oxide (GO) has been systematically studied using
various tools such as SEM, TEM, XRD, Fourier transform infrared spectroscopy
(FT-IR), X-ray photoemission spectroscopy (XPS), 13C solid state NMR, and O
K-edge X-ray absorption near edge structure (XANES). The TEM data reveal that
GO consists of amorphous and crystalline phases. The XPS data show that some
carbon atoms have sp3 orbitals and others have sp2 orbitals. The ratio of sp2
to sp3 bonded carbon atoms decreases as sample preparation times increase. The
13C solid-state NMR spectra of GO indicate the existence of -OH and -O- groups
for which peaks appear at 60 and 70 ppm, respectively. FT-IR results
corroborate these findings. The existence of ketone groups is also implied by
FT-IR, which is verified by O K-edge XANES and 13C solid-state NMR. We propose
a new model for GO based on the results; -O-, -OH, and -C=O groups are on the
surface.
