One Pot Synthesis of Graphene through Microwave Assisted Liquid Exfoliation of Graphite in Different Solvents

This study presents an easy and quick method for the synthesis of graphene from graphite in a set of solvents, including n-Hexadecane (n-Hexa), dimethylsulfoxide (DMSO), sodium hydroxide (NaOH), 1-octanol (OCTA), perchloric acid (PA), N,N-Dimethylformamide (DMF), ethylene glycol (EG), and ethylene diamine (ED), via microwave (MW) energy. The properties of final products were determined by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and the four-point probe technique. The XRD spectra of most of the MW-assisted graphene products showed peaks at 2θ = 26.5° and 54°. Layer numbers extend from 2 and 25, and the leading comes about were gotten by having two-layered products, named as graphene synthesized in dimethylsulfoxide (G-DMSO), graphene synthesized in ethylene glycol (G-EG), and graphene synthesized in 1-octanol (G-OCTA). G-DMF has the highest electrical conductivity with 22 S/m. The electrical conductivity is higher when the dipole moment of the used solvent is between 2 and 4 Debye (D). The FTIR spectra of most of the MW-assisted graphene products are in line with commercial graphene (CG). The UV-Vis spectra of all MW-assisted graphene products showed a peak at 223 nm referring to characteristic sp2 C=C bonds and 273 nm relating to the n → π * transition of C-O bonds

Green Synthesis of Graphene from Graphite in Molten Salt Medium

Green synthesis of graphene from graphite was carried out in molten salt mixture of LiCl-KCl, which is an environmentally friendly alternative to traditional methods using a large number of chemicals. The effect of carbonization temperature on the final properties of graphene products was investigated at a temperature range of 500-800°C. The layer numbers of graphene products were determined as a single layer and few layers by XRD and Raman analyses. The highest conductivity value of 1219 S/m was reached with the sample synthesized at 600°C (GGr600), which is 10-fold higher than that of commercial graphene (CG) (115 S/m). The percentage of carbon contents of GGr600 and sample synthesized at 800°C (GGr800) was determined as 86% and 73% by XPS. From the SEM analyses, it was observed that graphene products have sheet-like structures. A TEM image showed that GGr800 has the thickness changing from 5-9 nm, pointing out the graphene with few layers. AFM analysis demonstrated that GGr600 has a single-layer sheet-like structure