Huming Ren

A green approach to the synthesis of reduced graphene oxide nanosheets under UV irradiation

We present a totally green approach towards the synthesis and stabilization of aqueous graphene dispersions through UV-irradiated reduction of exfoliated graphene oxide (GO). Polyvinyl pyrrolidone (PVP) is used to enhance the dispersibility of reduced graphene oxide (RGO) by one-step functionalization. The proposed method is low cost and easy without using any photocatalysts or reducing agents, which can open up a new possibility for green preparation of stable RGO dispersions in large-scale production.

Co-precipitation synthesis and electrochemical properties of graphene supported LiMn1/3Ni1/3Co1/3O2 cathode materials for lithium-ion batteries

Nanostructured graphene supported LiMn1/3Ni1/3Co1/3O2 has been prepared by the co-precipitation method and used as the cathode material for lithium-ion batteries. The structure and morphology of the composite were examined using atomic force microscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and x-ray diffraction. The composite cathodes made of graphene nanosheet supported LiMn1/3Ni1/3Co1/3O2 showed superior electrochemical performance and increased capacity compared to raw LiMn1/3Ni1/3Co1/3O2 electrodes. The outstanding electrochemical behavior of graphene supported LiMn1/3Ni1/3Co1/3O2 was ascribed to the increased electrical conductivity and high structural stability resulting from the addition of graphene.

Intrinsic structure and friction properties of graphene and graphene oxide nanosheets studied by scanning probe microscopy

In this paper, atomic structure of single-layered graphene oxide (GO) and chemically reduced graphene oxide (CRGO) nanosheets was investigated using atomic force microscopy and scanning tunneling microscopy (AFM and STM). Furthermore, friction properties of the graphene and GO nanosheets were studied by frictional force microscopy (FFM). STM imaging provided direct evidence and the morphology was influenced by oxygen-containing groups and defects. The atomic scale structural disorder in a hexagonal two-dimensional network of carbon atoms changes the surface condition, which also caused the frictional property variations of the samples.

Compressive mechanical properties of porous GO materials prepared from freeze-drying method

In this paper porous graphene oxide (GO) foams were prepared from freeze-drying method. Compressive mechanical properties of GO foams with different density were investigated by uniaxial compression experiments and finite element (FE) simulation. GO foam exhibited excellent elasticity, which recovered to its original length even after 300 cycles. The structural evolution during the compression was revealed by FE simulation.