Structural, optical and electronic characteristics of N-doped graphene nanosheets synthesized using urea as reducing agent and nitrogen precursor

In the present study, nitrogen (N)-doped graphene nanosheets (NGns) have been synthesized by solvothermal method using urea both as the green precursor of N and as the reducing agent for graphene oxide (GO). As synthesized NGns have been characterized by x-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM) and x-ray photon spectroscopy (XPS). The Raman D to G band intensity ratio (ID/IG), being a measure of defects in the honeycomb lattice, is used as an indicator for the formation of NGns. For GO: urea weight ratio of 1:5, high C to O atomic ratio (C/O) of similar to 8.75 with an N-content as high as similar to 8.3 at.% and high I-D/I-G ratio of 1.55 have been observed, which confirm the removal of oxygen functionalities from GO to form NGns. Further, transparent conducting films (TCFs) of the synthesized NGns have been fabricated by spray coating. Thermal graphitization of the TCFs has been performed to enhance their optical and electrical properties. When annealed at 900 degrees C for 1 h in vacuum, the film shows a best performance in terms of sheet resistance and transmittance values of similar to 1.63 k Omega rectangle(-1) and similar to 68.21%, respectively.