Thermal Transformations of Chromium Acetylacetonate on Silica Surface

Babich, Igor V.; Plyuto, Yuri V.; Voort, Pascal Van Der; Vansant, Etienne F.

doi:10.1006/jcis.1997.4798

Cited by 52 publications

(43 citation statements)

References 18 publications

(14 reference statements)

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“…2,3,[6][7][8][9] Chromium acetylacetonate, or Cr(acac) 3 , appears especially promising as an RFB active species: it has five accessible redox states, and there is a wide voltage separation between the first reduced and first oxidized states of the neutral complex. The Cr(acac) 3 complex has also been used for catalysis 10 and as a standard for atomic absorption spectra. 11 Whereas vanadium acetylacetonate, or V(acac) 3 , appears to support outer-sphere electron transfer for both single-electron addition and withdrawal in certain nonaqueous electrolytes, and to undergo both charge exchanges with relatively facile kinetics, 12 the voltammetric response of Cr(acac) 3 is harder to interpret.…”

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Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Saraidaridis

Bartlett

Monroe

2016

J. Electrochem. Soc.

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Chromium acetylacetonate, or Cr(acac) 3 , is a promising active species for high-energy-density symmetric redox flow batteries because the neutral complex supports multiple charge-transfer reactions with widely separated redox potentials. Voltammetric and spectroelectrochemical measurements were performed to probe the mechanism of the first electrochemical disproportionation of Cr(acac) 3 -i.e., the cell reaction associated with the two redox couples immediately adjacent to the equilibrium potential of a freshly prepared nonaqueous Cr(acac) 3 solution. Substantially different limiting currents are observed for the positive and negative half-reactions, suggesting that at least one deviates from the similar outer-sphere single-electron transfer mechanisms proposed earlier. Spectroelectrochemical chronoamperometry suggests ligand dissociation in the negative reaction, and consequent structural reorganization of the Cr(acac) 3 complex. Vanadium acetylacetonate was investigated for comparison, and no ligand dissociation was observed. A negative half-reaction mechanism consistent with the voltammetric and spectroelectrochemical data is proposed, and used to rationalize observations of charge/discharge behavior in cycling Cr (acac) As researchers have identified the economic benefits that largescale energy storage delivers to the grid, research into redox flow batteries (RFBs) has expanded.1 In efforts to increase energy density or decrease active-species loading, researchers have targeted nonaqueous RFB chemistries, which can produce operating potentials outside the stability window of water.2-8 Several nonaqueous chemistries are based on transition-metal-centered coordination complexes. 2,3,[6][7][8][9] Chromium acetylacetonate, or Cr(acac) 3 , appears especially promising as an RFB active species: it has five accessible redox states, and there is a wide voltage separation between the first reduced and first oxidized states of the neutral complex. The Cr(acac) 3 complex has also been used for catalysis 10 and as a standard for atomic absorption spectra.11 Whereas vanadium acetylacetonate, or V(acac) 3 , appears to support outer-sphere electron transfer for both single-electron addition and withdrawal in certain nonaqueous electrolytes, and to undergo both charge exchanges with relatively facile kinetics, 12 the voltammetric response of Cr(acac) 3 is harder to interpret. Experimental efforts to clarify the electrochemistry of Cr(acac) 3 have been challenging because the reaction mechanism apparently varies with the choices of solvent, supporting electrolyte, and working electrode. 13-17The literature describing nonaqueous Cr(acac) 3 electrochemistry does not provide a consensus about the mechanisms for either the first reduction or first oxidation of the neutral complex. The electrochemical response during reduction depends heavily upon solvent, with different behavior observed in dimethylsulfoxide, 13,15,18,19 N,N-dimethylformamide, 15 dichloromethane, 14 acetonitrile, 15,17,20 and others. 15 Various mechanisms have...

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Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Saraidaridis

Bartlett

Monroe

2016

J. Electrochem. Soc.

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“…Therefore, the detection of SiCrO 4-5 Ϫ anions by s-SIMS technique indicates the formation of mixed silicon-chromium species during the activation process. This illustrates the anchorage of chromium oxidized species by reaction with the hydroxyl groups of silica surface [5,25,26].…”

Section: Activation Of Model Catalystmentioning

confidence: 86%

Activation processes and polyethylene formation on a phillips model catalyst studied by laser ablation, laser desorption, and static secondary ion mass spectrometry

Aubriet

Müller²,

Poleunis

et al. 2006

J. Am. Soc. Mass Spectrom.

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Since the discovery of the Phillips catalysts, there still is much uncertainty concerning their activation, their molecular structure, the nature of the active chromium sites, and the polymerization mechanisms. Surface techniques are not easy to be used for such study according to the nonconductive behavior of the support. Therefore, model Phillips catalyst is elaborated by spin coating a trivalent chromium precursor on a silicon wafer. The surface characterization of this model catalyst is conducted by laser ablation mass spectrometry (LA-MS), laser desorption/ionization mass spectrometry (LDI-MS), and static secondary ion mass spectrometry (s-SIMS), at different steps of its preparation. To validate our approach, a comparison is also made between the model and the real Philips catalyst. Moreover, the model catalyst efficiency for polyethylene synthesis is evaluated and allows us to discuss the validity of the mechanisms previously proposed to explain the catalytic process. The characterization of Phillips model catalyst by mass spectrometry allows us to better understand the activation processes of such catalyst. Depending on the activation temperature, chromium oxide species are formed and anchored at the support surface. They consist mainly in mono-chromium sites at high temperature. The chromium valence is hexavalent. This model catalyst is active for the polymerization of ethylene. A pseudo-oligomer molecular weight distribution is observed by LA-MS, whereas s-SIMS allows us to elucidate the anchorage of the polymer at activate chromium surface sites. (J Am Soc Mass Spectrom 2006, 17, 406 -414)

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“…The Cr(acac) 3 molecule may bind to the support surface due to formation of hydrogen bonds with hydroxyl groups. [5,11,[15][16][17] In the case of the alumina support, the electron donor-acceptor interaction [4,16] should also be considered. The chemical interaction of Cr(acac) 3 molecules with surface active sites may result in the formation of Cr(acac) x (x < 3) species on the support surface.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][11][12][13] Since the surface structures of SiO 2 and Al 2 O 3 supports have been very well reported in literature, speculations about Cr(acac) 3 binding at their surface were already being considered. [1,4,5,11,[15][16][17] Currently, two alternative mechanisms of the binding of Cr(acac) 3 at silica and alumina surface active sites are being debated. The Cr(acac) 3 molecule may bind to the support surface due to formation of hydrogen bonds with hydroxyl groups.…”

Section: Introductionmentioning

confidence: 99%

TPD‐MS and IR Studies of Cr(acac)₃ Binding Upon CVD at Silica and Alumina Surfaces

Davydenko

Mischanchuk

Pokrovskiy

et al. 2011

Chemical Vapor Deposition

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Thermal Transformations of Chromium Acetylacetonate on Silica Surface

Cited by 52 publications

References 18 publications

Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Activation processes and polyethylene formation on a phillips model catalyst studied by laser ablation, laser desorption, and static secondary ion mass spectrometry

TPD‐MS and IR Studies of Cr(acac)₃ Binding Upon CVD at Silica and Alumina Surfaces

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Thermal Transformations of Chromium Acetylacetonate on Silica Surface

Cited by 52 publications

References 18 publications

Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Activation processes and polyethylene formation on a phillips model catalyst studied by laser ablation, laser desorption, and static secondary ion mass spectrometry

TPD‐MS and IR Studies of Cr(acac)3 Binding Upon CVD at Silica and Alumina Surfaces

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TPD‐MS and IR Studies of Cr(acac)₃ Binding Upon CVD at Silica and Alumina Surfaces