The electron paramagnetic resonance (EPR) spectroscopy is a powerful and
sensitive method to detect intrinsic and extrinsic paramagnetic point defects in a
material system. EPR has recently been proven an effective tool for studying the lattice
defect of nanostructured carbon materials. In particular, EPR can be used to elucidate
the spin properties, including unpaired spins, conduction electrons, and dangling bonds
as well as the electronic states of different carbon nanostructures. EPR studies on
point-defects of carbon materials such as graphene and carbon nanotubes help to
unearth several electronic and optical features of the materials. Though the magnetic
feature of graphene has been studied intensively, EPR research on graphene and
graphene-like structures is still a new field. This chapter focuses on discussing EPR
investigations on graphene oxide, functional reduced graphene oxide, and carbon
nanotubes. In that, EPR has demonstrated as a suitable tool to detect spin density
changes in different functionalized nanocarbon materials. A novel approach to studying
the charge transfer within quantum dots-graphene hybrids, using continuous wave
EPR, will be discussed. It also enables the study of the change in the electronic
properties of graphene before and after attaching of quantum dots. This contributes to
improved understanding of electronic coupling effects in nanocarbon-nanoparticle
hybrid materials which are promising for various electronic and optoelectronic
applications.
Keywords: Carbon-centered radicals, Carbon nanotubes (CNTs), Charge transfer,
Curie’s law, Defects, Defect concentration, Electron spin delocalization, EPR
spectroscopy, Functionalized grapheme, Graphene oxide (GO), Number of spins, Oxidized CNT, Pauli-type paramagnetism, Photoluminescence, Quantum dots (QDs),
Reduced graphene oxide (rGO), Temperature dependence, Thiol-functionalized rGO
(TrGO), ZnO NP decorated rGO hybrid material (rGO-ZnO), ZnO NP decorated TrGO
(TrGO-ZnO).
