Facile synthesis of graphene oxide in a Couette–Taylor flow reactor

Park, Won Kyu; Kim, Hyeongkeun; Kim, Tae‐Young; Kim, Yena; Yoo, Se Hwa; Kim, Seungdu; Yoon, Dae Ho; Yang, Woo Seok

doi:10.1016/j.carbon.2014.11.024

Cited by 39 publications

(24 citation statements)

References 31 publications

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“…The GO was obtained from graphite (−200 mesh, 99.9999%, Alfa Aesar, Ward Hill, MA, USA) via the Hummers method [ 21 , 22 ]. The residual metal ions and acids in the GO were removed using a filter press system, which was well described in the previous report [ 23 ]. After the purification process, the residual impurities in the GO were measured via an X-ray photoelectron spectroscopy (XPS) analysis.…”

Section: Methodsmentioning

confidence: 99%

Impedance Spectroscopy Analysis and Equivalent Circuit Modeling of Graphene Oxide Solutions

Yoon

Kim

et al. 2017

Nanomaterials

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The optical and electrical characteristics of a graphene oxide solution (GS) with different graphene oxide (GO) concentrations in de-ionized water are investigated via the electrochemical impedance spectroscopy (EIS) method. The measurement results produced by the EIS for the GS are represented with both Bode and Nyquist plots in a frequency range from 1 kHz to 10 MHz. Using these results, we develop an equivalent circuit model as a function of the GO concentration, representing the GS as a mixed circuit of two-dimensional (2D) GO dispersed in parallel in de-ionized (DI) water. The underlying physics of the current-flowing behavior in the GS are explained and interpreted using empirical circuit models; the circuit model also shows that highly resistive GO becomes conductive in GS form in the DI water. The findings in this work should draw new attention toward GSes and related applications, including functional composite materials, catalysts, and filter membranes.

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Section: Methodsmentioning

confidence: 99%

Impedance Spectroscopy Analysis and Equivalent Circuit Modeling of Graphene Oxide Solutions

Yoon

Kim

et al. 2017

Nanomaterials

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“…GtO produced via the oxidation reaction (60 min) in shearing stress reactor was spectroscopically analyzed as shown in Fig. 1 44 . Fig.…”

Section: Resultsmentioning

confidence: 99%

High-efficiency exfoliation of large-area mono-layer graphene oxide with controlled dimension

Park

Yoon

Song

et al. 2017

Sci Rep

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In this work, we introduce a novel and facile method of exfoliating large-area, single-layer graphene oxide using a shearing stress. The shearing stress reactor consists of two concentric cylinders, where the inner cylinder rotates at controlled speed while the outer cylinder is kept stationary. We found that the formation of Taylor vortex flow with shearing stress can effectively exfoliate the graphite oxide, resulting in large-area single- or few-layer graphene oxide (GO) platelets with high yields (>90%) within 60 min of reaction time. Moreover, the lateral size of exfoliated GO sheets was readily tunable by simply controlling the rotational speed of the reactor and reaction time. Our approach for high-efficiency exfoliation of GO with controlled dimension may find its utility in numerous industrial applications including energy storage, conducting composite, electronic device, and supporting frameworks of catalyst.

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“…The formed HCs, Ga2O3, rGO, and GO were characterized using a field-emission scanning electron microscope (FE-SEM, S-4700, Hitachi, Tokyo, Japan) and X-ray diffraction (XRD; X'pert pro MPD, Philips, Amsterdam, The Netherlands). The GO was produced from the graphite via modified Hummer's method [20], and then the rGO was formed from the GO via thermal reduction in Ar at 750 °C for 1 h; their physical properties are shown in Figure 2. The photocatalytic reactions of the HCs and Ga2O3 were evaluated via the detection of the degradation of methylene blue (MB; C16H18N3SCl) at 245 nm of exposure in the dark to avoid any light source disturbance.…”

Section: Methodsmentioning

confidence: 99%

A Zero-Power, Low-Cost Ultraviolet-C Colorimetric Sensor Using a Gallium Oxide and Reduced Graphene Oxide Hybrid via Photoelectrochemical Reactions

et al. 2017

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A zero-power, low-cost ultraviolet (UV)-C colorimetric sensor is demonstrated using a gallium oxide and reduced graphene oxide (rGO) hybrid via photoelectrochemical reactions. A wide bandgap semiconductor (WBS) such as gallium oxide with an energy bandgap of 4.9 eV generates electron-hole pairs (EHPs) when exposed under a mercury lamp emitting 254 nm. While the conventional UVC sensors employing WBS convert the generated EHPs into an electrical signal via a solid-state junction device (SSD), our newly proposed UVC sensory system works by converting EHPs into an electrochemical reaction. The electrochemical reaction causes the degradation of a cationic thiazine redox dye, methylene blue (MB) and thereby spontaneously changes its color. As more rGO was hybridized with the gallium oxide, MB degradation was effectively expedited. Thus, the level of MB degradation under UVC can be evaluated as a UVC indicator. Unlike conventional SSD-based UVC sensors, our responsive colorimetric sensor can be applied where needed inexpensively and zero power.

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Facile synthesis of graphene oxide in a Couette–Taylor flow reactor

Cited by 39 publications

References 31 publications

Impedance Spectroscopy Analysis and Equivalent Circuit Modeling of Graphene Oxide Solutions

Impedance Spectroscopy Analysis and Equivalent Circuit Modeling of Graphene Oxide Solutions

High-efficiency exfoliation of large-area mono-layer graphene oxide with controlled dimension

A Zero-Power, Low-Cost Ultraviolet-C Colorimetric Sensor Using a Gallium Oxide and Reduced Graphene Oxide Hybrid via Photoelectrochemical Reactions

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