ChemInform Abstract: Rate Constants for H + O2 + M at 298 K for M: He, N2, and H2O

Hsu, K. J.; Durant, J. L.; Kaufman, F.

doi:10.1002/chin.198724028

Cited by 7 publications

(10 citation statements)

References 1 publication

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“…Such correction is justified because LDA-DFT yields an equilibrium volume that deviates from experimental observations by up to a few percent (e.g. [33]). In addition, we computed a Raman spectrum of C222 1 -CaCO 3 at 105 GPa ( Supplementary Table S3), which, expectedly, shows a C-O vibron frequency (996 cm -1 ) that is very close to that in P2 1 /c-CaCO 3 (1011 cm -1 ).…”

Section: Crystallographic Indexing Of the New Reflections Yields Monomentioning

confidence: 99%

Raman spectroscopy and x-ray diffraction of sp3CaCO3 at lower mantle pressures

et al. 2017

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The exceptional ability of carbon to form sp 2 and sp 3 bonding states leads to a great structural and chemical diversity of carbon-bearing phases at non-ambient conditions. Here we use laser-heated diamond anvil cells combined with synchrotron x-ray diffraction, Raman spectroscopy, and first-principles calculations to explore phase transitions in CaCO 3 at P > 40GPa. We find that post-aragonite CaCO 3 transforms to the previously predicted P2 1 /c-CaCO 3 with sp 3 -hybridized carbon at 105 GPa (~30 GPa higher than the theoretically predicted crossover pressure). The lowest enthalpy transition path to P2 1 /c-CaCO 3 includes reoccurring sp 2 -and sp 3 -CaCO 3 intermediate phases and transition states, as reveled by our variable-cell nudged elastic band simulation. Raman spectra of P2 1 /c-CaCO 3 show an intense band at 1025 cm -1 , which we assign to the symmetric C-O stretching vibration based on empirical and first principles calculations. This Raman band has a frequency that is ~20 % lower than the symmetric C-O stretching in sp 2 -CaCO 3 , due to the C-O bond length increase across the sp 2 -sp 3 transition, and can be used as a fingerprint of tetrahedrally-coordinated carbon in other carbonates.

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Section: Crystallographic Indexing Of the New Reflections Yields Monomentioning

confidence: 99%

Raman spectroscopy and x-ray diffraction of sp3CaCO3 at lower mantle pressures

et al. 2017

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“…The introduction of the Hubbard U term has been shown to improve the description of strongly correlated systems, and has now been used widely in studies of similar perovskites. [12][13][14][15] Compositions with oxygen deficiency up to d = 0.875 have been examined. We also use ab initio thermodynamics 16 to determine how the heat of formation of the non-stoichiometric composition varies under environmental conditions close to those reported experimentally.…”

Section: Introductionmentioning

confidence: 99%

First principles calculations of oxygen vacancy formation in barium-strontium-cobalt-ferrite

Zhang

Bristowe

2013

RSC Adv.

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Perovskite-type barium-strontium-cobalt-ferrite (BSCF) is a potentially significant material in the development of electrodes for solid oxide fuel cells and electrolysis cells, primarily because of its large oxygen vacancy concentration and mobility. Using density functional theory (DFT) with the DFT + U approach, we perform first principles calculations of oxygen vacancy formation in bulk BSCF with the composition Ba 0.5 Sr 0.5 Co 0.75 Fe 0.25 O 32d , in which a range of oxygen deficiencies (0.125 ¡ d ¡ 0.875) is investigated. Contrary to previous DFT studies for d = 0.125, DFT + U predicts that the non-stoichiometric structure is more stable than its stoichiometric counterpart with d = 0, and that this originates from a significantly different atomic and electronic structure following the introduction of the Hubbard U term in the calculations. As more vacancies are created there is no tendency for ordering and the total vacancy formation energy becomes positive and increases as the oxygen deficiency increases. Using ab initio thermodynamics, the heat of formation of BSCF as a function of oxygen partial pressure and temperature is determined and the results are in broad agreement with available stoichiometry measurements.

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“…In the H 2 /O 2 /Ar/H 2 O plasma, the main molecules in gas phase were H 2 , Ar, O 2 , and H 2 O molecule. As shown in Table , when the bath gas was H 2 O, the rate constants of reaction R12 to produce HO 2 intermediate is about 10, 25, and 16 times higher than that of H 2 , Ar, and O 2 , respectively

• H + O_{2} + M \to • {HO}_{2} + M

• H + O_{2} + H_{2} O \to {HO}_{2} • {normalH}_{2} O

…”

Section: Discussionmentioning

confidence: 98%

The promotion of Argon and water molecule on direct synthesis of H₂O₂from H₂and O₂

Wang

et al. 2017

AIChE Journal

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Direct synthesis of hydrogen peroxide (H2O2) from H2 and O2 is an ideal route. H2/O2 plasma has a great potential for direct synthesis of high purity H2O2 without purification operations. However, low yield and high energy consumption limits the application of H2/O2 plasma in industry. This article reports that gas state Ar and H2O molecule serving as molecular catalysts promoted the synthesis of H2O2 from H2/O2/Ar/H2O plasma dramatically: the H2O2 yield was enhanced by 244% and the energy consumption was reduced by 70.9%. Ar not only increased the electron density, but also selectively accelerated the dissociation of H2 toward the formation of •HO2, a key intermediate species in H2O2 synthesis. While H2O facilitated the formation of •HO2 radical and stabilized it by forming a HO2•H2O complex, resulting in enhancing the H2O2 production. This single molecular catalysis reduced the cost of H2O2 synthesis more than 50%. © 2017 American Institute of Chemical Engineers AIChE J, 64: 981–992, 2018

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ChemInform Abstract: Rate Constants for H + O2 + M at 298 K for M: He, N2, and H2O

Abstract: have been measured by the discharge‐flow technique to be 2.6·10‐32, 6.1·10‐32, and 6.4·10‐31 cm6s‐1 respectively.

Cited by 7 publications

References 1 publication

Raman spectroscopy and x-ray diffraction of sp3CaCO3 at lower mantle pressures

Raman spectroscopy and x-ray diffraction of sp3CaCO3 at lower mantle pressures

First principles calculations of oxygen vacancy formation in barium-strontium-cobalt-ferrite

The promotion of Argon and water molecule on direct synthesis of H₂O₂from H₂and O₂

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ChemInform Abstract: Rate Constants for H + O2 + M at 298 K for M: He, N2, and H2O

Abstract: have been measured by the discharge‐flow technique to be 2.6·10‐32, 6.1·10‐32, and 6.4·10‐31 cm6s‐1 respectively.

Cited by 7 publications

References 1 publication

Raman spectroscopy and x-ray diffraction of sp3CaCO3 at lower mantle pressures

Raman spectroscopy and x-ray diffraction of sp3CaCO3 at lower mantle pressures

First principles calculations of oxygen vacancy formation in barium-strontium-cobalt-ferrite

The promotion of Argon and water molecule on direct synthesis of H2O2from H2and O2

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The promotion of Argon and water molecule on direct synthesis of H₂O₂from H₂and O₂