Graphene-based nanostructures are recognized as smart materials and have attracted much attention due to their outstanding properties as well as emerging applications. Among them, vertical graphene network (VGN) with large surface area could be promising material as a platform for electrochemical and bio applications. VGN is composed of few-layer graphenes standing almost vertically on the substrate to form self-supported 3-dimensional structure. VGN and similar materials can be synthesized by plasma-enhanced chemical vapor deposition (PECVD) on heated substrates (600-800˚C) using methane and hydrogen mixtures. The height of VGN increases almost linearly with the growth period, while the thickness of each sheet and interspaces between adjacent sheets are almost constant. VGN is sometimes decorated with nanoparticles and biomolecules. The maze-like architecture of VGN with large surface-area graphene planes would be useful as electrodes for energy storage devices and scaffold for cell culturing. Especially, combined with surface functionalization including surface termination and decoration with nanoparticles and biomolecules, VGN can be suitable as platform in electrochemical and bio applications. Most important factors affecting morphology, crystallinity and growth rate of VGN are the balance between carbon precursors and H atoms in the plasma,and ion energy/ flux incident on the substrate as well as on the growing surface. Morphology of carbon nanostructures should be controlled according to their applications. We report the current status of the synthesis of VGN using several PECVD techniques, and focus on the control of their structures during the growth processes as well as surface decoration to be used as platform of the electrochemical and bio applications. Electrochemical experiments demonstrate that VGN offers great promise for providing a new class of nanostructured electrodes for electrochemical sensing, biosensing and energy conversion applications.
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