Xiaorui Ji

Synthesis of reduced graphene oxide/Cu nanoparticle composites and their tribological properties

The reduced graphene oxide/Cu nanoparticle (RGO–Cu NP) composites were synthesized by a facile and effective chemical reduction method. The morphology and structure of the RGO–Cu NP composites were characterized by X-ray diffraction, scanning electron microscopy, and Fourier trans form-infrared spectroscopy. The results indicated that Cu nanoparticles (Cu NPs) were well distributed on RGO nanosheets with an average diameter of 20 nm. The performance of the RGO–Cu NP composites as a lubricating oil additive was investigated by employing a ball–plate tribotester. It showed improved wear resistance and load-carrying capacity over those in the oil with RGO nanosheets. Scanning electron microscopy performed to analyze the wear scar surfaces after friction confirmed that the outstanding lubrication performance of composites could be attributed to their extremely thin laminated structure and the synergistic effect mechanism of RGO–Cu NP composites in base oil.

Facile synthesis and characterization of hexagonal NbSe{sub 2} nanoplates

Graphical abstract: - Highlights: • Uniform hexagonal NbSe{sub 2} nanoplates were prepared by a simple solid state reaction. • The possible formation mechanism of the NbSe{sub 2} nanoplates was discussed. • The formation of NbSe{sub 2} nanoplates undergoes a series of phase transition. - Abstract: The NbSe{sub 2} nanoplates with hexagonal morphology have been successfully prepared by a facile, environmentally friendly reaction in closed reactor at moderate temperature. The thermal (750 °C) solid-state reaction between the ball-milled mixture of micro-sized Nb and Se yielded a high yield of NbSe{sub 2} nanoplates. The as-prepared products were characterized by XRD, EDS, and SEM. The results showed that the as-prepared products were hexagonal phase NbSe{sub 2} nanoplates with uniform sizes and the formation of NbSe{sub 2} nanoplates underwent a series of phase transition. On the basis of experimental results obtained at different temperatures, a reasonable reaction process and a formation mechanism were proposed. Moreover, the ball milling time played a crucial role in acquiring the homogeneous distribution nanoplates.