• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.31-37
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• 2023

Owing to the rapid climate change, a high-performance energy storage system (ESS) for efficient energy consumption has been receiving considerable attention. ESS, such as capacitors, usually has issues with the ion diffusion of electrode materials, resulting in a decrease in their capacitance. Notably, appropriate pore diameter and large specific surface area (SSA) may result in an effective ion diffusion. Therefore, graphene and multi-walled carbon nanotube (graphene@MWCNT) hybrid nanomaterials, with covalent bonds between the graphene and MWCNT, were prepared via an edge-chemistry reaction. The properties of these materials, such as high porosity, large SSA, and high electroconductivity, make them suitable to be used as electrode materials for capacitors. The optimal ratio of graphene to MWCNT can affect the electrochemical performance of the electrode material based on its physical and electrochemical properties. The supercapacitor using optimal graphene-based hybrid electrode material exhibited highest specific capacitance value as 158 F/g and excellent cycle stability.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.235-240
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• 2013

Pure-carbon materials such as graphite, graphene, carbon nanotubes, and diamond have very high thermal conductivities. The reported thermal conductivity of graphene is in the range 3000~5000W/m-K at room temperature. Here, we developed graphene/cu foam hybrid type heat spreader to obtain higher thermal conductivity than Cu foam. Hybrid materials were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and thermal conductivity measurement system; LFA (Laser Flash Analysis @ LFA 447, NETZSCH). We suggest that excellent thermal properties of graphene/cu foam hybrid structures are beneficial for all proposed electrical applications and can lead to a thermal management application.

• Membrane Journal
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• v.21 no.3
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• pp.247-255
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• 2011

In this study, to obtain good dispersity of graphene which has excellent conductivity and mechanical strength, the graphene was modified by two different methods. Then the SPAES/graphene hybrid membranes were fabricated from different graphene contents. We compared performance of composite membrane with different preparing method of graphene and content of modified graphene. The morphology of the composite membranes has been investigated using SEM. Chemical structure of modified graphene was analyzed using by FT-IR and EDX. The proton conductivity and methanol permeability of the hybrid membranes were studied with changing graphene content from 0.5 to 3.0 wt.%. The SPAES/modified graphene composite membranes showed high proton conductivity (0.21 S/cm) compared with the SPAES membrane (0.09 S/cm) at $80^{\circ}C$ and 100% relative humidity condition. And the methanol permeability was decreased linearly as the content of modified graphene increased from 0 to 1.5 wt%.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.42-46
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• 2012

The effect of the parameters for few-layered graphene growth by thermal CVD on nickel substrate was investigated. Graphene can be synthesized by using different strategies. Chemical vapor deposition (CVD) has known as one of the most attractive methods to produce graphene due to its good film uniformity, compatibility and large scale production. The control of parameters such as temperature, growth time and pressure in CVD process has been widely recognized as the most important process in graphene growth. Different carbon precursors, methane and acetylene, were introduced in the quartz tube with a variety of growth conditions. Raman spectroscopy was used to confirm the presence of a few- or multi-layered graphene.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3269-3273
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• 2013

Graphene oxide (GO) has been of particular interest because it provides unique properties due to its high surface area, chemical functionality and ease of mass production. GO is produced by chemical exfoliation of graphite and is decorated with oxygen-containing groups such as phenol hydroxyl, epoxide groups and ionizable carboxylic acid groups. Due to the presence of those functional groups, GO can be utilized as a novel platform for hybrid nanocomposites in chemical synthetic approaches. In this work, GO-$SnO_2$ nanocomposites have been prepared through the spontaneous formation of molecular hybrids. When $SnO_2$ precursor solution and GO suspension were simply mixed, $Sn^{2+}$ was spontaneously formed into $SnO_2$ nanoparticles upon the deoxygenation of GO. Through further chemical reduction by adding hydrazine, reduced GO-$SnO_2$ hybrid was finally created. Our investigation for the electrocapacitive properties of hybrid electrode showed the enhanced performance (389 F/g), compared with rGO-only electrode (241 F/g). Our approach offers a scalable, robust synthetic route to prepare graphene-based nanocomposites for supercapacitor electrode via spontaneous hybridization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.175-185
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• 2023

A hybrid supercapacitor is a promising energy storage device in view of its excellent capacitive performance. Commercial three-dimensional foam nickel (Ni) can be used as an ideal framework due to an interconnected network structure. However, its application as an electrode material for supercapacitors is limited due to its low specific capacity. Herein, we report a successful growth of MnO₂ on the surface of graphene by a one-step hydrothermal method; thus, forming a three-dimensional MnO₂-graphene-Ni hybrid foam. Our results show that the mixed structure of MnO₂ with nanoflowers and nanorods grown on the graphene/Ni foam as a hybrid electrode delivers the maximum specific capacitance of 193 F·g^-1 at a current density 0.1 A·g^-1. More importantly, the hybrid electrode retains 104% of its initial capacitance after 1,000 charge-discharge cycles at 1 A·g^-1; thus, showing the potential application as a stable supercapacitor electrode.

• Journal of Sensor Science and Technology
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• v.29 no.3
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• pp.201-204
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• 2020

In this study, we fabricated and evaluated graphene composite based 3D scaffolds and planar films. The hybrid composite was prepared by mixing a calculated amount of graphene nanopowder and polydimethylsiloxane in tetrahydrofuran solution. The hybrid composite is easy to manufacture into various forms using direct printing technology or a pressing method. A 3D scaffold structure was prepared at ambient temperature with a flow rate of 240 mm/min. The nozzle pressure was maintained at 350 kPa by adjusting the viscosity of the composite material. The planar film was prepared at different thicknesses using a roll-to-roll equipment. The prepared hybrid nanocomposites were evaluated to investigate their electrical properties according to temperature and mechanical deformation. The obtained results were consistent with each other. Therefore, it can be used effectively as sensors through shape definition.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.25-37
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• 2020

In this study, hybridization of graphene oxide and metal was carried out by the functional groups containing oxygen and thermal treatment for reduction in order to enhance the electrical conductivity and magnetic properties of graphene materials. Graphene-metal hybrid materials were synthesized using the oxygen-containing functional groups (-OH, -COOH and so on) on the surface of graphene oxide by replacing them with metal ions via ion exchange method as well as thermal reduction. The metals used in this study were Fe, Ag, Ni, Zn, and Fe/Ag, and it was confirmed that metal particles of uniform size were well dispersed on the graphene surface through SEM, TEM, and EDS. All of the metal particles on the graphene surface had an oxide-crystalline structure. To check the electrical properties, sheet resistance of the rGO-metal hybrid sample was measured on the PET film made by the dip-coating, and the specific resistance was calculated by measuring the thickness of the specimen through SEM. As a result, the specific resistance was in the range of 2.14×10-5 and 3.5×10-3 ohm/cm.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.581-585
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• 2014

We conducted investigation on the hybridization of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT : PSS) with graphene derivative (G-PSS), which has been prepared by wrapping reduced graphene oxide (RGO) with PSS. In situ polymerization of PEDOT/PSS in the presence of G-PSS afforded the PEDOT/PSS and graphene hybrid (GP). The analysis of XPS, IR and Raman spectroscopies for GP showed that PEDOT/PSS was successfully synthesized and hybridized with graphene. Compared to the G-PSS, GP showed an enhanced electrical conductivity of $4.46{\times}10^2S/m$ with a good wter-dispersity.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.434.2-434.2
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• 2014

We observe enhanced pH response of solution-gated field-effect transistors (SG-FET) having 1D-2D hybrid channel of vertical grown ZnO nanorods grown on CVD graphene (Gr). In recent years, SG-FET based on Gr has received a lot of attention for biochemical sensing applications, because Gr has outstanding properties such as high sensitivity, low detection limit, label-free electrical detection, and so on. However, low-defect CVD Gr has hardly pH responsive due to lack of hydroxyl group on Gr surface. On the other hand, ZnO, consists of stable wurtzite structure, has attracted much interest due to its unique properties and wide range of applications in optoelectronics, biosensors, medical sciences, etc. Especially, ZnO were easily grown as vertical nanorods by hydrothermal method and ZnO nanostructures have higher sensitivity to environments than planar structures due to plentiful hydroxyl group on their surface. We prepared for ZnO nanorods vertically grown on CVD Gr (ZnO nanorods/Gr hybrid channel) and to fabricate SG-FET subsequently. We have analyzed hybrid channel FETs showing transfer characteristics similar to that of pristine Gr FETs and charge neutrality point (CNP) shifts along proton concentration in solution, which can determine pH level of solution. Hybrid channel SG-FET sensors led to increase in pH sensitivity up to 500%, compared to pristine Gr SG-FET sensors. We confirmed plentiful hydroxyl groups on ZnO nanorod surface interact with protons in solution, which causes shifts of CNP. The morphology and electrical characteristics of hybrid channel SG-FET were characterized by FE-SEM and semiconductor parameter analyzer, respectively. Sensitivity and sensing mechanism of ZnO nanorods/Gr hybrid channel FET will be discussed in detail.