Xuecheng Chen

Low-Temperature Exfoliated Graphenes: Vacuum-Promoted Exfoliation and Electrochemical Energy Storage

A preheated high-temperature environment is believed to be critical for a chemical-exfoliation-based production of graphenes starting from graphite oxide, a belief that is based on not only experimental but also theoretical viewpoints. A novel exfoliation approach is reported in this study, and the exfoliation process is realized at a very low temperature, which is far below the proposed critical exfoliation temperature, by introducing a high vacuum to the exfoliation process. Owing to unique surface chemistry, low-temperature exfoliated graphenes demonstrate an excellent energy storage performance, and the electrochemical capacitance is much higher than that of the high-temperature exfoliated ones. The low-temperature exfoliation approach presents us with a possibility for a mass production of graphenes at low cost and great potentials in energy storage applications of graphene-based materials.

One-pot self-assembly of three-dimensional graphene macroassemblies with porous core and layered shell

The innate character of graphene, defined as the basic unit of sp2carbon materials, provides opportunities for the design and construction of carbon nanostructures with tuned properties. Here, we report a novel three-dimensional graphene macroassembly with a core–shell structure starting from reduced graphene oxides (RGO) by a one-pot self-assembly process under very mild conditions. In the presence of KMnO4, such an assembly process is initiated by low-temperature heating below 100 °C at atmospheric pressure and is totally free from a severe hydrothermal process. Such a core–shell structure is characterized by a porous core and layered membrane shell, and the macro-morphology and infrastructure of the macroassembly are well controllable and tunable. The macroassembly presented here and its self-assembly preparation directly from graphene nanosheets present the first example of the simultaneous formation of a coaxial hybrid infrastructure in a graphene-based nanostructured material, and such a core–shell structured macroassembly shows potential for use in energy storage and other applications.