Hydrogen migration dynamics in hydrated Al clusters: The Al{sub 17}{sup (−)}·H{sub 2}O system as an example

Álvarez-Barcia, S.

doi:10.1063/1.4866583

Title: Hydrogen migration dynamics in hydrated Al clusters: The Al{sub 17}{sup (−)}·H{sub 2}O system as an example

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Abstract

The Al{sub m}{sup (−)}·(H{sub 2}O){sub n} systems are known to undergo water splitting processes in the gas phase giving H{sub k}Al{sub m}(OH){sub k}{sup (−)}·(H{sub 2}O){sub n−k} systems, which can generate H{sub 2}. 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 H{sub 2} 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 HAl{sub 17}(OH){sup (−)}, 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 Al{sub 17}{sup (−)}·(H{sub 2}O) → HAl{sub 17}(OH){sup (−)}, 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.more »« less

Authors:: Álvarez-Barcia, S.

Publication Date:: Fri Feb 28 00:00:00 EST 2014

OSTI Identifier:: 22255054

Resource Type:: Journal Article

Journal Name:: Journal of Chemical Physics

Additional Journal Information:: Journal Volume: 140; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DENSITY FUNCTIONAL METHOD; HYDROGEN; INTERACTIONS; MIGRATION; MOLECULAR DYNAMICS METHOD; SURFACES; TUNNEL EFFECT; WATER

Citation Formats


                    Álvarez-Barcia, S., and Flores, J. R., E-mail: flores@uvigo.es. Hydrogen migration dynamics in hydrated Al clusters: The Al{sub 17}{sup (−)}·H{sub 2}O system as an example.  United States: N. p., 2014. 
        Web.  doi:10.1063/1.4866583.

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                    Álvarez-Barcia, S., & Flores, J. R., E-mail: flores@uvigo.es. Hydrogen migration dynamics in hydrated Al clusters: The Al{sub 17}{sup (−)}·H{sub 2}O system as an example.  United States.  https://doi.org/10.1063/1.4866583

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                    Álvarez-Barcia, S., and Flores, J. R., E-mail: flores@uvigo.es. 2014.  
        "Hydrogen migration dynamics in hydrated Al clusters: The Al{sub 17}{sup (−)}·H{sub 2}O system as an example".  United States.  https://doi.org/10.1063/1.4866583.

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@article{osti_22255054,

  title        = {Hydrogen migration dynamics in hydrated Al clusters: The Al{sub 17}{sup (−)}·H{sub 2}O system as an example},

  author       = {Álvarez-Barcia, S. and Flores, J. R., E-mail: flores@uvigo.es},

  abstractNote = {The Al{sub m}{sup (−)}·(H{sub 2}O){sub n} systems are known to undergo water splitting processes in the gas phase giving H{sub k}Al{sub m}(OH){sub k}{sup (−)}·(H{sub 2}O){sub n−k} systems, which can generate H{sub 2}. 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 H{sub 2} 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 HAl{sub 17}(OH){sup (−)}, 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 Al{sub 17}{sup (−)}·(H{sub 2}O) → HAl{sub 17}(OH){sup (−)}, 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 H{sub 2} generation from the interaction of Al clusters and water molecules are discussed.},

  doi          = {10.1063/1.4866583},

  url          = {https://www.osti.gov/biblio/22255054},
  journal      = {Journal of Chemical Physics},

  issn         = {0021-9606},

  number       = 8,

  volume       = 140,

  place        = {United States},

  year         = {Fri Feb 28 00:00:00 EST 2014},

  month        = {Fri Feb 28 00:00:00 EST 2014}

}

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