Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment

Abstract

Electron paramagnetic resonance (EPR) spectroscopy has been applied to different chemically treated reduced graphene oxide (rGO) and multiwalled carbon nanotubes (CNTs). A narrow EPR signal is visible at g = 2.0029 in both GO and CNT-Oxide from carbon-related dangling bonds. EPR signals became broader and of lower intensity after oxygen-containing functionalities were reduced and partially transformed into thiol groups to obtain thiol-functionalized reduced GO (TrGO) and thiol-functionalized CNT (CNT-SH), respectively. Additionally, EPR investigation of CdSe quantum dot-TrGO hybrid material reveals complete quenching of the TrGO EPR signal due to direct chemical attachment and electronic coupling. Our work confirms that EPR is a suitable tool to detect spin density changes in different functionalized nanocarbon materials and can contribute to improved understanding of electronic coupling effects in nanocarbon-nanoparticle hybrid nano-composites promising for various electronic and optoelectronic applications.

Electron scattering in graphene with adsorbed NaCl nanoparticles

“…This line corresponded to g ¼ 2.0027 and originated from a SiC substrate. 18 We were not able to detect any carbon like ESR signal that has been reported for functionalized graphene oxide [19][20][21] and could be related to graphene layer. In case of the NaCl-treated graphene, several additional lines were observed for magnetic field in the range between 0.31 T and 0.38 T. 22 These lines were very well visible for magnetic field perpendicular to the sample surface however, with deviation of an angle from perpendicular orientation, a rapid decrease in their amplitude was observed.…”

Development of a chitin/graphene oxide hybrid composite for the removal of pollutant dyes: Adsorption and desorption study

“…This result indicates an increment of moieties in the nGO structure which would be responsible for the increase in signal. Other researchers have proposed that these moieties would correspond to the oxidized groups such as -OH and -COOH produced during the oxidation of graphite [28]. In the case of bulk graphite the ESR line is Dysonian due to the skin effect, characteristic of conductive materials, whereas the nGO spectrum presents a single Lorentzian curve suggesting a loss of conductivity which represents another evidence of the introduction of defects in graphite structure due to oxidation [29].…”

Preparation and characterization of partially reduced graphene oxide aerogels doped with transition metal ions

“…Other reported in the literature method of obtaining GO without Mn contamination is done by the use of different oxidizing agents, e.g. HNO 3 /H 2 SO 4 instead of KMnO 4 [64]. Reference (pristine) prGO aerogel presents a weak EPR signal which consists of two components with similar g factors (g = 2.00), but one has the linewidth of 0.38 mT and small intensity, and the second 9.2 mT and much stronger intensity.…”