Graphene oxide nanosheets synthesized by ultrasound: Experiment versus MD simulation

Graphene oxide nanosheets were synthesized via facile and fast procedure by ultrasonic bath (GO-U). The specific surface area, number of layers and other interesting parameters of these samples were compared with graphene oxide prepared by classical method (GO-C). Seven techniques including UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), transmission electron microscopy, thermal gravimetric (TG) analysis, BET surface area, and Raman spectroscopy were used to characterize the GO samples. According to XRD analysis, GO-U samples showed fewer layers than GO-C samples. The TG analysis indicated that the graphene oxide prepared with 20 min ultrasonic irradiation (GO-U20) has more oxygen-containing functional groups on its surface and edges with respect to that of 50 min sonication (GO-U50). The BET specific surface area indicated that GO-U20 showed larger surface area than that of GO-U50. The binding energy, deformation energy, and formation energy were calculated for GO structures as a function of OH groups with different O/C ratios using molecular dynamics (MD) simulation. The MD results showed that the GO with higher O/C and less OH groups has lower binding energy. This theoretical result confirmed the experimental data that GO-U20 has more chance to attach oxygen-containing functional groups than that of GO-U50. (C) 2018 Elsevier B.V. All rights reserved.