Aluminum hydration in the vapor phase

Oblath, Steven B.; Gole, James L.

doi:10.1063/1.437175

Cited by 33 publications

(29 citation statements)

References 16 publications

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“…The use of this criterion C. RRKM calculations: Sensitivity to tunneling and anharmonicty, and variation with the energy Fig. 10 presents the results of the RRKM calculation, which employs the master equation (1). We have considered the four routes (A, B, C, and D) of the long circuit and their derivation to the short circuit.…”

Section: B MD Simulationsmentioning

confidence: 99%

“…Al atoms have been found to react with individual water molecules [1][2][3][4][5][6][7][8][9][10] and also in conditions of microhydration. [11][12][13] Relay (Grotthuss-type) mechanisms and tunneling play a role in those reactions, which are of technological and astrophysical importance; Al oxide and hydroxide have recently been detected in the space.…”

Section: Introductionmentioning

confidence: 98%

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Hydrogen migration dynamics in hydrated Al clusters: The Al17(−)·H2O system as an example

Álvarez‐Barcia¹,

Flores²

2014

The Journal of Chemical Physics

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The Alm((-))·(H2O)n systems are known to undergo water splitting processes in the gas phase giving HkAlm(OH)k((-))·(H2O)n-k systems, which can generate H2. The migration of H atoms from one Al atom to another on the cluster's surface is of critical importance to the mechanism of the complete H2 production process. We have applied a combination of Molecular Dynamics and Rice-Ramsperger-Kassel-Marcus theory including tunneling effects to study the gas-phase evolution of HAl17(OH)((-)), which can be considered a model system. First, we have performed an extensive search for local minima and the connecting saddle points using a density functional theory method. It is found that in the water-splitting process Al17((-))·(H2O) → HAl17(OH)((-)), the H atom which bonds to the Al cluster losses rather quickly its excess energy, which is easily "absorbed" by the cluster because of its flexibility. This fact ultimately determines that long-range hydrogen migration is not a very fast process and that, probably, tunneling only plays a secondary role in the migration dynamics, at least for moderate energies. Reduction of the total energy results in the process being very much slowed down. The consequences on the possible mechanisms of H2 generation from the interaction of Al clusters and water molecules are discussed.

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Section: B MD Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Hydrogen migration dynamics in hydrated Al clusters: The Al17(−)·H2O system as an example

Álvarez‐Barcia¹,

Flores²

2014

The Journal of Chemical Physics

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“…There appears to have been no previous observations of HCuCl. However, there have been numerous experimental, − and theoretical − examples of metal atoms inserting into covalent bonds.…”

Section: Discussionmentioning

confidence: 99%

Laser-Induced Fluorescence and Mass Spectrometric Studies of the Cu + HCl Reaction over a Wide Temperature Range. Formation of HCuCl

et al. 1996

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The kinetics and products of the Cu + HCl reaction have been studied using high-temperature fast-flow reactors (HTFFR). The rate coefficient measurements were made using laser-induced fluorescence (LIF) of Cu atoms and yielded k(680-1500 K) ) 1.2 × 10 -10 exp(-7719 K/T) cm 3 molecule -1 s -1 . Product analysis was achieved by coupling a specially designed HTFFR to a chopped molecular beam quadrupole mass spectrometer. Those observations, which covered the approximately 1150-1500 K temperature range, showed formation of CuCl and the previously unknown species HCuCl. Confirmation of the latter assignment was made using DCl. Increasing pressure and decreasing temperature favor the HCuCl formation. These findings and this molecular structure are supported by ab initio calculations. These also indicate passage through a CuClH f HCuCl transition state as the rate-controlling step for formation of both products, in agreement with the observed pressure independence of the overall, Cu disappearance, rate coefficients.

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“…Aluminum is known an energy storage material with pretty high gravimetric energy density (31.1 MJ/kg) and the stored chemical potential energy enables large energy-favorable hydrogen evolution reaction (HER) from water (2Al + 6H 2 O → 2Al(OH) 3 + 3H 2 , △H = −861.1 kJ) . For this aim, extensive investigations have been conducted via various means to crush Al into fine powers in order to circumvent the surface oxide (e.g., by doping metal additives like gallium). , In recent years, the HER investigations of water on metal clusters has been an important subject of researchers working in a few interdisciplines. − For example, Castleman, Khanna, and their colleagues reported an interesting study on the reactivity of aluminum cluster anions with water in a gas flow tube, and they found that Al 16 – , Al 17 – , and Al 18 – result in spontaneous production of H 2 from water, while Al 12 – reacts to form Al 12 H 2 O – as Al 12 – binds water tightly and Al 12 H 2 O – bears a stable structure. In comparison, clusters (such as Al 11 – and Al 13 – ) bearing insurmountable energy-transition states have low reactivity toward water; while those (like Al 14 – and Al 16 – ) having open electronic shells do not support the product observation of water adsorption.…”

Section: Introductionmentioning

confidence: 99%

How Partial Atomic Charges and Bonding Orbitals Affect the Reactivity of Aluminum Clusters with Water?

et al. 2018

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We present here a further insight on the hydrogen evolution reactions (HER) of aluminum clusters with one and multiple water molecules. Along with natural bond orbital (NBO) and frontier molecular orbital (FMO) analysis, we compared the reactivities of both anionic and neutral Al, Al, Al, and Al clusters with water in gas phase. It is found that electron flow interactions between these typical Al clusters and HO initiate their reactions, allowing varied charge distribution on the cluster. With an emphasis on the typical Al cluster, we checked out the reactive intermediates, activated complexes, transition states, bond breaking and stereochemistry for it to react with two and four water molecules, respectively. The kinetic- and thermodynamic- allowed reaction pathways are coincident with the experimental observation of Al (OH) being dominant products for Al clusters reacting with water. It is illustrated how additional water molecules function as catalysts enabling strengthened HER activity.

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Aluminum hydration in the vapor phase

Cited by 33 publications

References 16 publications

Hydrogen migration dynamics in hydrated Al clusters: The Al17(−)·H2O system as an example

Hydrogen migration dynamics in hydrated Al clusters: The Al17(−)·H2O system as an example

Laser-Induced Fluorescence and Mass Spectrometric Studies of the Cu + HCl Reaction over a Wide Temperature Range. Formation of HCuCl

How Partial Atomic Charges and Bonding Orbitals Affect the Reactivity of Aluminum Clusters with Water?

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