ABSTRACT
Highly reactive radicals or chemicals are generated on the surfaces of oxide semiconductors via reactions between photo-induced charges and ambient gas molecules. These radicals or chemicals have been utilized in heterogeneous photosynthesis and photocatalysis. In this study, we demonstrated that the photocatalytic reactions on the surface of ZnO promoted the oxidation and decomposition of graphene. Raman spectra were used to analyze the evolution of the G and 2D peaks. The oxidation of graphene on a ZnO substrate by UV radiation was faster than that in the absence of ZnO. During oxidation, the resistivity and the transmittance of graphene also increased. The XPS results showed that functional groups related to the oxidation of graphene were formed during the photocatalytic reactions. This simple and clean approach will be also effective for selective surface modification by enhancing the surface chemical reactions that pattern graphene via oxidation.
ABSTRACT
A chemical defect healing of reduced graphene oxide (RGO) was carried out via intramolecular cross-dehydrogenative coupling (ICDC) with FeCl3 at room temperature. The Raman intensity ratio of the G-band to the D-band, the IG/ID ratio, of the RGO was increased from 0.77 to 1.64 after the ICDC reaction. From XPS measurements, the AC=C/AC-C ratio, where the peak intensities from the C=C and C-C bonds are abbreviated as AC=C and AC-C, of the RGO was increased from 2.88 to 3.79. These results demonstrate that the relative amount of sp(2)-hybridized carbon atoms is increased by the ICDC reaction. It is of great interest that after the ICDC reaction the electrical conductivity of the RGO was improved to 71 S cm(-1), which is 14 times higher than that of as-prepared RGO (5 S cm(-1)).
