Physisorption-induced change in the magnetism of microporous carbon

Sato, Hirohiko; Kawatsu, Naoki; Enoki, Toshiaki; Endo, Morinobu; Kobori, Ryoji; Maruyama, Satoshi; Kaneko, Katsumi

doi:10.1016/j.carbon.2006.09.017

Cited by 25 publications

(15 citation statements)

References 20 publications

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“…Figure 8 shows the adsorption isotherm and the spin susceptibility » s of ACFs in adsorption/desorption of H 2 O molecules. 38 The adsorption isotherm shows an on/off feature with a threshold vapor pressure of P t /P 0 µ 0.5 (P 0 : the saturation vapor pressure); no adsorption takes place in the low vapor pressure range below P t due to the hydrophobic nature of nanographene sheet, while the adsorption starts above P t and it is rapidly saturated just after P t . The magnetic susceptibility, which is proportional to the strength of the magnetic moment of the edge-state spin, tracks the behavior of the isotherm with fidelity.…”

Section: Magnetic Switching Phenomenonmentioning

confidence: 99%

“…39 The magnetic switching phenomenon is universal, and can be observed for other guest molecules though the behavior is modified depending on their chemical features. 40 Here, the key point is the presence of hydroxy group as we can know by comparing various guest molecules with and without hydroxy group, as summarized in Figure 10 with H 2 O, CH 3 OH, C 2 H 5 OH, (CH 3 ) 2 CO, C 6 H 6 , CHCl 3 , CCl 4 , C 6 H 12 , C 6 H 14 , as physisorbed guests. The repulsive force works between a hydrophobic nanographene sheet and a molecule having a hydroxy group, whereas organic molecules with no hydroxy group attractively interact with nanographene sheet.…”

Section: Magnetic Switching Phenomenonmentioning

confidence: 99%

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Magnetic Edge State of Nanographene and Unconventional Nanographene-Based Host–Guest Systems

Enoki¹,

Takai²,

Kiguchi³

2012

Bulletin of the Chemical Society of Japan

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Nanographene, nanosized fragments of graphene, has edge-shape-dependent electronic structures different from those of infinite size graphene. Around the zigzag-shaped edges of a nanographene sheet, a nonbonding edge state of ³-electron origin is created, which is the origin of electronic and chemical activities of nanographene. In addition, the strongly spin-polarized edge state has localized spin, giving magnetic activity. We investigate the magnetic properties of nanoporous activated carbon fibers consisting of a three-dimensional disordered network of nanographite domains, each of which is a stack of 34 nanographene sheets, in relation to hostguest interaction. Chemically inert guest species such as water, organic solvent, or argon, physisorptively condensed into the nanopores mechanically compress the nanographite domains, resulting in high spin/low spin magnetic switching of the edge-state spins. The presence of an energy gap and the nanographene edges decorated by oxygen-containing functional groups make nanographene less amphoteric, modifying charge-transfer mechanisms in the hostguest interaction. HNO 3 shows a two-step charge-transfer process. In Br adsorption, physisorbed Br species cooperate with charge-transfer Br species, giving an interesting interplay of charge transfer and magnetic switching phenomena. In the K adsorption, physisorbed K atoms form antiferromagnetic K clusters in the nanopores, while a portion of K species are responsible for charge transfer. The reaction with fluorine creates magnetic ·-dangling bond states, at the expense of the ³-conjugated electron system. The interplay between the edge-state spins and the ·-dangling bond spins gives a variety of magnetism depending on the fluorine concentration.

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Section: Magnetic Switching Phenomenonmentioning

confidence: 99%

Section: Magnetic Switching Phenomenonmentioning

confidence: 99%

Magnetic Edge State of Nanographene and Unconventional Nanographene-Based Host–Guest Systems

Enoki¹,

Takai²,

Kiguchi³

2012

Bulletin of the Chemical Society of Japan

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“…Furthermore, it should be noted that the magnetism of the edgestate spins is affected by the interaction with guest species [10][11][12]. Recently, it has been reported that the magnetic structure of edge-state spins is modified by the mechanical compression of nanographite domains (stacked nanographene sheets) by guest molecules condensed in the nanopores in the nanographene-based nanoporous carbon (activated carbon fiber (ACF)) [13][14][15].…”

Section: Introductionmentioning

confidence: 98%

Magnetism of nanographene network influenced by the interaction with acid species

Enoki

Tsuge

Hao

et al. 2010

Journal of Physics and Chemistry of Solids

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“…It is very common that graphenebased materials contain a lot of oxygen functional groups at the surface [5] and it seems that these groups are responsible for the good adsorption properties of active carbons. This is especially important in case of adsorption of water and other species containing the -OH groups, as pure graphene is strongly hydrophobic [6]. We have already shown that the adsorption of molecules in the active carbons significantly influences their electronic properties, having big impact on the localization of the charge carriers within their structure [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

EPR and Impedance Measurements of Graphene Oxide and Reduced Graphene Oxide

et al. 2017

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We report the observations of electron paramagnetic resonance and impedance measurements of graphene oxide and reduced graphene oxide performed in the wide temperature range in order to get insight into the electronic properties of graphene-based materials and the role of oxygen functionalities in the charge carrier transport phenomena. In such systems the strong spin localization, hopping charge carrier transport as well as the formation of adsorption layers are observed, all the phenomena changing significantly after the heavily oxidized graphene is reduced.

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Physisorption-induced change in the magnetism of microporous carbon

Cited by 25 publications

References 20 publications

Magnetic Edge State of Nanographene and Unconventional Nanographene-Based Host–Guest Systems

Magnetic Edge State of Nanographene and Unconventional Nanographene-Based Host–Guest Systems

Magnetism of nanographene network influenced by the interaction with acid species

EPR and Impedance Measurements of Graphene Oxide and Reduced Graphene Oxide

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