Activation routes for high surface area graphene monoliths from graphene oxide colloids

Wang, Shuwen; Tristan, Ferdinando; Minami, Daiki; Fujimori, Toshihiko; Cruz-Silva, Rodolfo; Terrones, Mauricio; Takeuchi, Kenji; Teshima, Katsuya; Rodríguez‐Reinoso, F.; Endo, Morinobu; Kaneko, Katsumi

doi:10.1016/j.carbon.2014.04.071

Cited by 87 publications

(45 citation statements)

References 66 publications

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“…The monolith of graphene oxide and KOH mixture was heated up to 573 K in Ar to reduce the graphene oxide and then the monolith of the graphene-KOH mixture was heated to 1073 K in order to activate the graphene. The preceding X-ray photoelectron spectroscopic study showed that heating at 573 K in Ar reduced the graphene oxide sufficiently [31].…”

Section: Preparation and High Temperature Treatment Of Highly Porous mentioning

confidence: 94%

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Comparative pore structure analysis of highly porous graphene monoliths treated at different temperatures with adsorption of N2 at 77.4 K and of Ar at 87.3 K and 77.4 K

Wang

Minami

Kaneko

2015

Microporous and Mesoporous Materials

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Abstract:We prepared nanoporous graphene monolith of different porosity by high temperature treatment up to 2073 K in Ar. The porosity is comparatively evaluated with N2 adsorption isotherms at 77.4 K and Ar adsorption isotherms at 87.3 K and 77.4 K. N2 adsorption at 77.4 K shows an excess adsorption amount below 3 × 10 -3 of the relative pressure which is caused by the quadrupole moment of an N2 molecule. This effect doesn't give significant influence on the determination of the total surface area from subtracting pore effect (SPE) method, the micropore volume from Dubinin-Radushkevich (DR) method and the total pore volumes from the Gurvitch rule.However, the peak of the micropore size distribution determined by Horvath-Kawazoe (HK) method from N2 adsorption at 77.4 K shifts to a smaller size than that from Ar adsorption at 87.3 K by 0.05 to 0.09 nm.

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Section: Preparation and High Temperature Treatment Of Highly Porous mentioning

confidence: 94%

“…Highly porous graphene monoliths developed by these authors consist of nanographenes, which have a wide range of pores from micropores to macropores [31].…”

Section: Introductionmentioning

confidence: 99%

Comparative pore structure analysis of highly porous graphene monoliths treated at different temperatures with adsorption of N2 at 77.4 K and of Ar at 87.3 K and 77.4 K

Wang

Minami

Kaneko

2015

Microporous and Mesoporous Materials

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“…As nanoporous graphene monolith (NGM) has a wide-range of pores from micropores and mesopores (Wang et al 2014) and the crystallinity of the graphene walls can be controlled (Wang et al 2016), the water adsorption study on NGM should provide useful information on water adsorption mechanism on hydrophobic nanoporous carbons. This article describes the correlation of water adsorption amount with the pore volume of micropores and small mesopore of NGM.…”

Section: Introductionmentioning

confidence: 99%

Cluster-associated filling of water molecules in graphene-based mesopores

2016

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Graphene monoliths were prepared through unidirectional freeze-drying method of graphene oxide colloids-KOH mixed solution and successive reduction by heating at 573 K in Ar. The porosity-and crystallinitycontrolled graphene monoliths were prepared by the KOH activation at different temperature and the post-heating in Ar. These activated graphene monoliths were characterized by N 2 adsorption at 77 K, X-ray diffraction and Raman spectroscopy. Water adsorption isotherms show a typical hydrophobicity below P/P 0 = 0.5 and a marked hydrophilicity above P/P 0 = 0.6, which depends on the pore width. In the water adsorption isotherms of porous graphene monoliths activated at different temperature, the higher the activation temperature, the larger the rising P/P 0 . No essential change in the shape of the water adsorption isotherm for the post-heated nanoporous graphene monoliths is observed except for the decrease in water adsorption amount with higher post-heating temperature. The linear relationship between the saturated water adsorption and pore volume whose width is smaller than 4 nm indicates clearly that water molecules are adsorbed in small mesopores by the clusterassociated filling mechanism.

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“…Nevertheless, in this approach a post-carbonization additional activation need to be applied to develop the microporosity. Another method is based on soft templates and usually the triblock copolymers (F127) are used as templates [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…Although the development of porosity in monoliths is essentially important, the methods proposed lead to materials that are not superior to activated carbons in this aspect [3][4][5][6][7][8]. Of course the shape and mechanical stability of a monolith is essential for industrial applications where powdered activated carbon are rather not desired.…”

Section: Introductionmentioning

confidence: 99%

Robust graphene-based monoliths of homogeneous ultramicroporosity

Bandosz

Wang

Minami

et al. 2015

Carbon

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Graphite oxide (GO) and graphene monoliths were prepared using the unidirectional freezing of GO water suspension. These materials were saturated with a poly(4 ammonium styrene sulfonic acid) water soluble polymer and then carbonized at 1123 K. This process increases significantly the materials strength and density. A uniform deposition of the polymer-derived carbon on the external layers of the graphene sheets of the monolith was found. The carbon from polymer not only provided more contact between the graphene sheets but apparently increased the overall graphitization level (based on Raman spectra). The modification decreased the electrical resistance by one order of magnitude compared to that of the graphene monolith. N2 adsorption at 77 K showed that the thus-treated graphene monoliths has quite homogenous pores with the pore width of 0.7 nm. These pores combined with large transport pores and conductive properties make the monoliths tested the promising materials for separation, energy storage and/or gas sensing. The tunability of the properties and pore structure of the robust graphene untramicroporous monolith through the control of chemistry of the initial GO monolith was shown.

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Activation routes for high surface area graphene monoliths from graphene oxide colloids

Cited by 87 publications

References 66 publications

Comparative pore structure analysis of highly porous graphene monoliths treated at different temperatures with adsorption of N2 at 77.4 K and of Ar at 87.3 K and 77.4 K

Comparative pore structure analysis of highly porous graphene monoliths treated at different temperatures with adsorption of N2 at 77.4 K and of Ar at 87.3 K and 77.4 K

Cluster-associated filling of water molecules in graphene-based mesopores

Robust graphene-based monoliths of homogeneous ultramicroporosity

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