Graphite intercalation co
mpounds (GICs) can be considered stacks of individual doped graphene layers. Here we de
monstrate a reversible for
mation of sulfuric acid-based GICs using a
mmoniu
m persulfate as the che
mical oxidizing agent. No covalent che
mical oxidation leading to the for
mation of graphite oxide occurs, which inevitably happens when other co
mpounds such as potassiu
m per
manganate are used to charge carbon layers. The resulting acid/persulfate-induced stage-1 and stage-2 GICs are characterized by suppression of the 2D band in the Ra
man spectra and by unusually strong enhance
ment of the G band. The G band is selectively enhanced at different doping levels with different excitations. These observations are in line with recent reports for che
mically doped and gate-
modulated graphene and support newly proposed theories of Ra
man processes. At the sa
me ti
me GICs have so
me advantageous differences over graphene, which are de
monstrated in this report. Our experi
mental observations, along with earlier reported data, suggest that at high doping levels the G band cannot be used as the reference peak for nor
malizing Ra
man spectra, which is a co
mmonly used practice today. A Fer
mi energy shift of 1.20鈥?.25 eV and 1.0 eV was esti
mated for the stage-1 and stage-2 GICs, respectively, fro
m the Ra
man and optical spectroscopy data.
Keywords:
mpounds&qsSearchArea=searchText">graphite intercalation compounds; graphene; man+spectroscopy&qsSearchArea=searchText">Raman spectroscopy; mi+energy&qsSearchArea=searchText">Fermi energy; ment&qsSearchArea=searchText">enhancement