NMR Study of Preferential Endohedral Adsorption of Methanol in Multiwalled Carbon Nanotubes

Liu, Xin; Pan, Xiulian; Shen, Wenjie; Ren, Pengju; Han, Xiuwen; Bao, Xinhe

doi:10.1021/jp300138x

Cited by 26 publications

(26 citation statements)

References 49 publications

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“…This phenomenon could be attributed to the high adsorption ability of graphene48. Similar observation was also reported in the NMR study on the adsorption of methanol on CNTs28. The weakly adsorbed anions were discovered at the electrolyte loading volume of 75 μL (as schematically shown in the “status 2”).…”

Section: Resultssupporting

confidence: 82%

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Solid-state NMR Study of Ion Adsorption and Charge Storage in Graphene Film Supercapacitor Electrodes

Yan

et al. 2016

Sci Rep

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Graphene film has been demonstrated as promising active materials for electric double layer capacitors (EDLCs), mainly due to its excellent mechanical flexibility and freestanding morphology. In this work, the distribution and variation pattern of electrolyte ions in graphene-film based EDLC electrodes are investigated with a 11B magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy. For neutral graphene films soaked with different amounts of electrolytes (1 M TEABF4/ACN), weakly and strongly adsorbed anions are identified based on the resonances at different 11B chemical shifts. Unlike other porous carbonaceous materials, the strongly adsorbed anions are found as the major electrolyte anions components in graphene films. Further measurements on the ion population upon charging are carried out with applying different charging voltages on the graphene films. Results indicate that the charging process of graphene-film based EDLCs can be divided into two distinct charge storage stages (i.e., ejection of co-ions and adsorption of counter-ions) for different voltages. The as-obtained results will be useful for the design and fabrication of high performance graphene-film based EDLCs.

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Section: Resultssupporting

confidence: 82%

“…reported the adsorption of water and phosphorus-containing compounds on activated carbons21222324, where distinct resonances corresponding to the adsorbed and non-adsorbed molecules were observed. Similar observation was also presented for the adsorption of water2526, hydrogen2627, and methanol28 inside carbon nanotubes (CNTs). Forse et al 29.…”

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confidence: 79%

Solid-state NMR Study of Ion Adsorption and Charge Storage in Graphene Film Supercapacitor Electrodes

Yan

et al. 2016

Sci Rep

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“…If the moiety is situated close enough to these domains, the electronic effect is to shift the nuclei response upfield of TMS. This type of unusual interaction has been best documented for molecules adsorbed on porous carbon [90–93]. The other unusual feature is the simplicity of the 1 H spectra of SSVCT‐02 and ‐05 when the corresponding 13 C spectra are as complicated as the other samples.…”

Section: Discussionmentioning

confidence: 85%

LX‐17 Thermal Decomposition‐Characterization of Solid Residues from Cook‐Off in a Small‐Scale Vessel Under Confinement

Reynolds

Muetterties

Nelson

et al. 2021

Propellants Explo Pyrotec

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Concerns surround whether insensitive (or any) energetic materials are more dangerous to handle when exposed to abnormal thermal environments. This study characterizes the residual material remaining after LX‐17 (92.5 % 1,3,5‐triamino 2,4,6‐trinitro benzene (TATB) and 7.5 % Kel‐F) is exposed to various thermal environments in a sealed small‐scale vessel cook‐off test reactor (heated at 0.1 to 100 °C/min until the reactor opened at 3000 psi (20.7 MPa)). Previous work has shown no additional sensitivity of these residues as evaluated by small‐scale safety analysis, but characterization on the molecular scale indicates the TATB is transformed to more reactive compounds as well as the residue could be precursors to toxic gases. The solids and chars were characterized by various analytical methods. Heat‐flow measurements indicated exothermic release is due to a mixture of residual TATB and related decomposition products (which may be more energetic). The N/C and O/N ratios indicated a material much more degraded than TATB. Primarily, the solids were a network of amorphous C inter‐dispersed with N and O. Types of bonding include C−C, C−N, N−H, N−C, N=C, N≡C, C−O=, and −OH. Solvent extracts of the solids showed TATB decomposition intermediates benzo‐furazans and benzo‐furoxans, substituted TATB (mono‐nitroso, hydroxyl, and chlorinated) along with several unidentified smaller molecules. These results indicate thermal treatment produces an amorphous carbon residue with heteroatoms incorporated through differing functionality, varying depending upon the thermal severity of exposure. These structures also could further decompose producing toxic light gases (such as cyanide).

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“…44 , 45 , 46 , 47 , 48 Similar observations have also been reported for species adsorbed within carbon nanotubes. 49 , 50 The origin of the pronounced NMR frequency shift for in-pore species lies in the so-called "ring current" effect that arises due to the presence of delocalized electrons in the sp 2 -hybridised carbon surface. 51 Application of the external magnetic field, B 0, induces electron circulation within the delocalized π-orbitals, resulting in a secondary local magnetic field above the carbon surface that opposes the main field (as represented in Figure 2b).…”

Section: Identifying Adsorbed Species In Microporous Carbonmentioning

confidence: 99%

Solid-state NMR studies of supercapacitors

Griffin

Forse

Grey

2016

Solid State Nuclear Magnetic Resonance

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Electrochemical double-layer capacitors, or 'supercapacitors' are attracting increasing attention as high-power energy storage devices for a wide range of technological applications. These devices store charge through electrostatic interactions between liquid electrolyte ions and the surfaces of porous carbon electrodes. However, many aspects of the fundamental mechanism of supercapacitance are still not well understood, and there is a lack of experimental techniques which are capable of studying working devices. Recently, solid-state NMR has emerged as a powerful tool for studying the local environments and behaviour of electrolyte ions in supercapacitor electrodes. In this Trends article, we review these recent developments and applications. We first discuss the basic principles underlying the mechanism of supercapacitance, as well as the key NMR observables that are relevant to the study of supercapacitor electrodes.We then review some practical aspects of the study of working devices using ex situ and in situ methodologies and explain the key advances that these techniques have allowed on the study of supercapacitor charging mechanisms. NMR experiments have revealed that the pores of the carbon electrodes contain a significant number of electrolyte ions in the absence of any charging potential. This has important implications for the molecular mechanisms of supercapacitance, as charge can be stored by different ion adsorption/desorption processes. Crucially, we show how in situ NMR experiments can be used to quantitatively study and characterise the charging mechanism, with the experiments providing the most detailed picture of charge storage to date, offering the opportunity to design enhanced devices. Finally, an outlook for future directions for solid-state NMR in supercapacitor research is offered.3

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NMR Study of Preferential Endohedral Adsorption of Methanol in Multiwalled Carbon Nanotubes

Cited by 26 publications

References 49 publications

Solid-state NMR Study of Ion Adsorption and Charge Storage in Graphene Film Supercapacitor Electrodes

Solid-state NMR Study of Ion Adsorption and Charge Storage in Graphene Film Supercapacitor Electrodes

LX‐17 Thermal Decomposition‐Characterization of Solid Residues from Cook‐Off in a Small‐Scale Vessel Under Confinement

Solid-state NMR studies of supercapacitors

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