scholarly journals Room-Temperature Reduction of Graphene Oxide in Water by Metal Chloride Hydrates: A Cleaner Approach for the Preparation of Graphene@Metal Hybrids

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1255
Author(s):  
Patrick. P. Brisebois ◽  
Ricardo Izquierdo ◽  
Mohamed Siaj
Keyword(s):  
Graphene Oxide ◽  
Metal Oxide ◽  
Room Temperature ◽  
Structural Integrity ◽  
Metal Oxide Nanoparticles ◽  
Particle Diameter ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning ◽  
Metal Hybrids

Headed for developing minimalistic strategies to produce graphene@metal hybrids for electronics on a larger scale, we discovered that graphene oxide (GO)-metal oxide (MO) hybrids are formed spontaneously in water at room temperature in the presence of nothing else than graphene oxide itself and metal ions. Our observations show metal oxide nanoparticles decorating the surface of graphene oxide with particle diameter in the range of 10–40 nm after only 1 h of mixing. Their load ranged from 0.2% to 6.3% depending on the nature of the selected metal. To show the generality of the reactivity of GO with different ions in standard conditions, we prepared common hybrids with GO and tin, iron, zinc, aluminum and magnesium. By means of carbon-13 solid-state nuclear magnetic resonance using magic angle spinning, we have found that graphene oxide is also moderately reduced at the same time. Our method is powerful and unique because it avoids the use of chemicals and heat to promote the coprecipitation and the reduction of GO. This advantage allows synthesizing GO@MO hybrids with higher structural integrity and purity with a tunable level of oxidization, in a faster and greener way.

scholarly journals Preparation of Li3PS4–Li3PO4 Solid Electrolytes by Liquid-Phase Shaking for All-Solid-State Batteries

2021 ◽  
Vol 2 (1) ◽  
pp. 39-48
Author(s):  
Nguyen H. H. Phuc ◽  
Takaki Maeda ◽  
Tokoharu Yamamoto ◽  
Hiroyuki Muto ◽  
Atsunori Matsuda
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Liquid Phase ◽  
Room Temperature ◽  
Reaction Medium ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Synthesis Methods ◽  
Magic Angle ◽  
Angle Spinning

A solid solution of a 100Li3PS4·xLi3PO4 solid electrolyte was easily prepared by liquid-phase synthesis. Instead of the conventional solid-state synthesis methods, ethyl propionate was used as the reaction medium. The initial stage of the reaction among Li2S, P2S5 and Li3PO4 was proved by ultraviolet-visible spectroscopy. The powder X-ray diffraction (XRD) results showed that the solid solution was formed up to x = 6. At x = 20, XRD peaks of Li3PO4 were detected in the prepared sample after heat treatment at 170 °C. However, the samples obtained at room temperature showed no evidence of Li3PO4 remaining for x = 20. Solid phosphorus-31 magic angle spinning nuclear magnetic resonance spectroscopy results proved the formation of a POS33− unit in the sample with x = 6. Improvements of ionic conductivity at room temperature and activation energy were obtained with the formation of the solid solution. The sample with x = 6 exhibited a better stability against Li metal than that with x = 0. The all-solid-state half-cell employing the sample with x = 6 at the positive electrode exhibited a better charge–discharge capacity than that employing the sample with x = 0.

Intercalation of molecular species into the interstitial sites of fullerene

1992 ◽  
Vol 7 (8) ◽  
pp. 2136-2143 ◽  
Author(s):  
Roger A. Assink ◽  
James E. Schirber ◽  
Douglas A. Loy ◽  
Bruno Morosin ◽  
Gary A. Carlson
Keyword(s):  
Molecular Species ◽  
Room Temperature ◽  
Primary Resonance ◽  
Magic Angle Spinning ◽  
Hydrogen Gas ◽  
Magic Angle ◽  
Hydrogen Molecules ◽  
Fcc Lattice ◽  
Angle Spinning ◽  
A Minor

Molecular species were found to diffuse readily into the octahedral interstitial sites of the fcc lattice of C60. The 13C NMR spectrum of C60 under magic angle spinning (MAS) conditions consisted of a primary resonance at 143.7 ppm and a minor peak shifted 0.7 ppm downfield. The downfield shift obeys Curie's law and is attributed to the Fermi-contact interaction between paramagnetic oxygen molecules and all 60 carbon atoms of rapidly rotating adjacent C60 molecules. Exposure of C60 to 1 kbar oxygen for 1.75 h at room temperature resulted in a spectrum of seven evenly spaced resonances corresponding to the filling of 0 to 6 of the adjacent octahedral interstitial sites with oxygen molecules. The distribution of site occupancies about a C60 molecule provided evidence that the intercalation process is controlled by diffusion kinetics. Exposure to 0.14 kbar hydrogen gas at room temperature for 16 h filled a substantial fraction of the interstitial sites of C60 and C70 with hydrogen molecules.

Cocation Effects in Rhodium-Exchanged Y Zeolites

1987 ◽  
Vol 111 ◽  
Author(s):  
R. K. Shoemaker ◽  
R. A. Johnson ◽  
T. M. Apple
Keyword(s):  
Room Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Internuclear Separation ◽  
Y Zeolites ◽  
Yield Information ◽  
Acid Centers ◽  
Angle Spinning ◽  
Metal Electron ◽  
C Nmr

AbstractMagic-angle spinning13C NMR spectra of carbon monoxide adsorbed on rhodium/Y zeolites yield information about the proportioning of CO in the various possible adsorption states; linear, bridged and dicarbonyl. The relative amounts of these adsorbed types, particularly the ratio of bridged to linear CO is influenced by the nature of the majority cations present with the rhodium. Reduced Rh-Na(+) and Rh-Li(+) zeolites form all three CO surface species, while acidic Rh zeolites, formed by the introduction of the co-cations Ca(2+) and H(+), exhibit no bridged carbonyls. The suppression of the bridged moiety results from the withdrawal of electrons from rhodium by the acid centers making the metal electron deficient (more oxidized).Rh(I) dicarbonyl species form on all samples studied, however these species are indistinguishable from the linear monocarbonyls based solely upon the isotropic chemical shift obtained from magic-angle spinning. The number of dicarbonyl species can be quantitatively determined by the Carr- Purcell-Meiboom-Gill sequence, the powder pattern or by selective exchange experiments. At room temperature the two CO molecules in the gemdicarbonyl appear to undergo a mutual hopping exchange. This motion is frozen out at 198K. The carbon-carbon internuclear separation in the gemdicarbonyl is 3.3 Å.Catalysts pre-adsorbed with13CO undergo exchange of the dicarbonyl species upon exposure at 198 K to12CO, however they also react to form13CO2. When exposed to CO at room temperature no CO2formation is detected.

Cs Speciation in Cements

2000 ◽  
Vol 663 ◽  
Author(s):  
J. V. Hanna ◽  
L. P. Aldridge ◽  
E. R. Vance
Keyword(s):  
Silica Fume ◽  
Blast Furnace Slag ◽  
Room Temperature ◽  
Ordinary Portland Cement ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Water Leaching ◽  
Sharp Signal ◽  
Angle Spinning ◽  
Furnace Slag

ABSTRACTSolid-state 133Cs magic angle spinning nuclear magnetic resonance (MAS NMR) measurements have been used to investigate Cs speciation in cements designed for immobilizing low-level nuclear wastes. Cs in ordinary Portland cement cured for only 10 days at room temperature appears to only inhabit aqueous solutions, as evidenced by a sharp signal with no sidebands, whether or not substantial quantities of blast furnace slag or silica fume are present. No significant 133Cs spectral differences were observed when slag or silica fume were present for curing periods of 10 days, but differences due to Cs partly inhabiting crystalline sites instead of water solutions were observed after 12 months in the slag-containing cement. Pre- incorporation of Cs in various zeolites, followed by mixing the zeolites into the cement, leads to enhanced Cs retention in the cement when it is subject to water leaching at 25°C.

113Cd NMR studies of Hofmann-type clathrates and related compounds: Evidence for two room temperature orientational glasses

1990 ◽  
Vol 68 (12) ◽  
pp. 2270-2273 ◽  
Author(s):  
S. Nishikiori ◽  
C. I. Ratcliffe ◽  
J. A. Ripmeester
Keyword(s):  
Chemical Shift ◽  
Room Temperature ◽  
Magic Angle Spinning ◽  
Great Sensitivity ◽  
Magic Angle ◽  
Nmr Studies ◽  
Static Disorder ◽  
Orientational Glass ◽  
Angle Spinning ◽  
Related Compounds

113Cd magic angle spinning NMR, with and without 1H cross-polarisation and decoupling, has been used to study a number of Hofmann-type clathrates and related compounds. The 113Cd chemical shift shows a great sensitivity to the environment of Cd, even for complexes with closely related structures. The presence of five resonances due to Cd surrounded by CxN(4–x) (where x = 0 to 4) in Cd(CN)2 and Cd(CN)2•C6H12 indicates a static disorder of the CN groups, which makes these materials orientational glasses. Keywords: 113Cd NMR, Hofmann-type clathrates, Cd(CN)2, disorder, orientational glass.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

High Resolution Magic Angle Spinning NMR in Combinatorial Chemistry

2001 ◽  
Vol 4 (4) ◽  
pp. 333-351 ◽  
Author(s):  
G. Lippens ◽  
R. Warrass ◽  
J. Wieruszeski ◽  
P. Rousselot-Pailley ◽  
G. Chessari
Keyword(s):  
High Resolution ◽  
Combinatorial Chemistry ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Angle Spinning
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