• Journal of the Korean Applied Science and Technology
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• v.40 no.4
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• pp.913-923
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• 2023

In this study, a triboelectric nanogenerator was fabricated using the composite of teflon-based polymer and graphene flower, which are stable in air and have relatively high electronegativity. The composite was used to fabricate an electronegative layer of a nanogenerator using a spin-coating method. For the electropositive layer, a zinc oxide film was prepared using a sol-gel method. The fabricated triboelectric nanogenerator produced a maximum power of about 44 ㎼. In conclusion, since all the active layers of the triboelectric nanogenerator was made by the solution process, it is scalable to a large area.

• Carbon letters
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• v.13 no.2
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• pp.130-132
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• 2012

In this study, cobalt oxide ($Co_3O_4$)/graphene composites were synthesized through a simple chemical method at various calcination temperatures. We controlled the crystallinity, particle size and morphology of cobalt oxide on graphene materials by changing the annealing temperatures (200, 300, $400^{\circ}C$). The nanostructured $Co_3O_4$/graphene hybrid materials were studied to measure the electrochemical performance through cyclic voltammetry. The $Co_3O_4$/graphene sample obtained at $200^{\circ}C$ showed the highest capacitance of 396 $Fg^{-1}$ at 5 $mVs^{-1}$. The morphological structures of composites were also examined by scanning electron microscopy and transmission electron microscopy (TEM). Annealing $Co_3O_4$/graphene samples in air at different temperatures significantly changed the morphology of the composites. The flower-like cobalt oxides with higher crystallinity and larger particle size were generated on graphene according to the increase of calcination temperature. A TEM analysis of the composites at $200^{\circ}C$ revealed that nanoscale $Co_3O_4$ (~7 nm) particles were deposited on the surface of the graphene. The improved electrochemical performance was attributed to a combination effect of graphene and pseudocapacitive effect of $Co_3O_4$.