We have demonstrated a facile and efficient strategy for the fabrication of soluble reduced graphene oxide sheets （RGO） and the preparation of titanium oxide （TiO2） nanoparticle-RGO composites using a modified one-step hydrothermal method. It was found that graphene oxide could be easily reduced under solvothermal conditions with ascorbic acid as reductant, with concomitant growth of TiO2 particles on the RGO surface. The TiO2-RGO composite has been thoroughly characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Microscopy techniques （scanning electron microscopy, atomic force microscopy, and transmission electron microscopy） have been employed to probe the morphological characteristics as well as to investigate the exfoliation of RGO sheets. The TiOR-RGO composite exhibited excellent photocatalysis of hydrogen evolution.
Jianfeng Shen Min Shi Bo Yan Hongwei Ma Na Li Mingxin Ye
The Young＇s modulus of graphene with various rectangular and circular vacancy defects is investigated by molecular dynamics simulation. By comparing with the results calculated from an effective spring model, it is demonstrated that the Young＇s modulus of graphene is largely correlated to the size of vacancy defects perpendicular to the stretching direction. And a linear reduction of Young＇s modulus with the increasing concentration of monoatomic-vacancy defects （Le., the slope of =0.03） is also observed. The fracture behavior of graphene, including the fracture strength, crack initiation and propagation are then studied by the molecular dynamics simulation, the effective spring model, and the quantized fracture mechanics. The blunting effect of vacancy edges is demonstrated, and the characterized crack tip radius of 4.44 A is observed.
