Decoration of graphite nanoplatelets with Nb2O5 deposited by radio frequency sputtering

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The deposition of various nano-materials onto graphite nanoplatelets (layers of graphene) is ideal for different applications. The decoration of the meal oxide nanostructures onto graphite nanoplatelets (GNPs) by radio frequency sputtering technique have a great impact on the structure graphene sheets, because of the interaction of the sputtered atoms and energetic plasma species. The main focused in this research work to deposit a thin layer of Nb2O5 onto GNPs powder by varying radio frequency power and process pressures with powder vibration frequency in argon atmosphere. The structural properties of the samples were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Raman spectroscopy. For the chemical analysis of the samples X-ray photoelectron spectroscopy (XPS) was used. The interlayer d spacing of the GNPs calculated from the XRD pattern changes with Nb2O5 decoration. By increasing Nb2O5 contents through RF powers and process pressures variation defects on the surface of GNPs increased and basal planes of GNPs gradually loss their initial ordering, decreasing the degree of graphitization. TEM images demonstrated that GNPs decorated with around 5 to 10 nm uniform layer of Nb2O5 on their surface were successfully fabricated. The frequencies of the GNPs G and 2D modes were found to undergo red shifts with decoration of Nb2O5. We explained the red shift of GNPs from the Raman frequencies in terms of tensile strain and doping induced by Nb2O5. XPS analysis suggests that with deposition of Nb2O5 onto GNPs surface, the Fermi level of GNPs shifts downward gradually with increasing Nb2O5 contents due to a p-type doping effect.