Perla Balbuena - Academia.edu (original) (raw)

Papers by Perla Balbuena

Research paper thumbnail of Density functional theory analysis of reactivity of PtxPdy alloy clusters

Surface Science, 2007

We investigate the reactivity of various Pt xPd y combinations (with x + y = 10 and various x: y ... more We investigate the reactivity of various Pt xPd y combinations (with x + y = 10 and various x: y ratios) towards the adsorption of specific intermediates of the oxygen reduction, using the B3PW91 hybrid density functional theory. The reactivity is shown to be not only sensitive to the composition of the cluster, but also to the atomic distribution. The calculations indicate that two different ensembles: one ordered and one randomly mixed, with overall composition Pt 3Pd 7 are thermodynamically more favorable than pure Pt 10 for the oxygen reduction reaction. The reasons for this behavior are clearly explained in terms of the atomic and electronic distribution, which makes the Pd atoms to act as electron donors both to Pt atoms and to the adsorbates, thus the reactivity of the Pd atoms in such environment becomes intermediate between Pt and Pd. Moreover, it is found that in a mixed Pt 3Pd 7 state the electronic distribution makes the average atom more similar to Pt than to Pd, whereas in an ordered Pt 3Pd 7 cluster, the average atom is more similar to Pd than to Pt.

Research paper thumbnail of Adsorption and Dissociation of H 2 O 2 on Pt and Pt-Alloy Clusters and Surfaces

J Phys Chem B, 2006

The adsorption of H(2)O(2) on Pt and Pt-M alloys, where M is Cr, Co, or Ni, is investigated using... more The adsorption of H(2)O(2) on Pt and Pt-M alloys, where M is Cr, Co, or Ni, is investigated using density functional theory. Binding energies calculated with a hybrid DFT functional (B3PW91) are in the range of -0.71 to -0.88 eV for H(2)O(2) adsorbed with one of the oxygen atoms on top Pt positions of Pt(3), Pt(2)M, and PtM(2), and enhanced values in the range of -0.81 to -1.09 eV are found on top Ni and Co sites of the Pt(2)M clusters. Adsorption on top sites of Pt(10) yields a weaker binding of -0.48 eV, whereas on periodic Pt(111) and Pt(3)Co(111) surfaces, H(2)O(2) generally dissociates into two OH radicals. On the other hand, attempts to attach H(2)O(2) on bridge sites cause spontaneous dissociation of H(2)O(2) into two adsorbed OH radicals, suggesting that stable adsorptions on bridge sites are not possible for any of the clusters or extended surfaces that are being studied. We also found that the water-H(2)O(2) interaction reduces the strength of the adsorption of H(2)O(2) on these clusters and surfaces.

Research paper thumbnail of Combined ab Initio Quantum Mechanics and Classical Molecular Dynamics Studies of Polyphosphazene Polymer Electrolytes: Competitive Solvation of Li + and LiCF 3 SO 3

Research paper thumbnail of A Density Functional Theory Study of Adsorption and Decomposition of Nitroamine Molecules on the Al(111) Surface

The Journal of Physical Chemistry C

... E-mail: kostas.termentzidis@univie.ac.at and juergen.hafner@univie.ac.at ... Details of the c... more ... E-mail: kostas.termentzidis@univie.ac.at and juergen.hafner@univie.ac.at ... Details of the calculated adsorption geometries are compiled in table 1, together with adsorption energies with respect to gas-phase Au (Eads > 0 meaning exothermic adsorption). ...

Research paper thumbnail of Yan-JPCA-110

Research paper thumbnail of 389539 Role and Stability of a Metal Carbide Catalyst in the Growth of Single-Walled Carbon Nanotubes

Achieving a high degree of selectivity in the synthesis of single-walled carbon nanotubes in a sy... more Achieving a high degree of selectivity in the synthesis of single-walled carbon nanotubes in a systematic and efficient way is one major barrier to be overcome before the exceptional properties of these materials can be exploited commercially. Many studies seem to indicate that the state and structure of the catalyst in CCVD play a fundamental role in determining structural features of the nanotubes such as chirality. Selective growth has been reported in both monometallic and carbide nanoparticles; however the contribution that either of them brings to this process has not been completely elucidated. The stability and the influence of the latter in the growing nanotube structure is the focus of this study. We determine the stability and relevant features of carbide nanoparticles and the interactions between carbide facets and the nascent carbon structure using ab initio molecular dynamics simulations. We use 55-metal-atom Ni and Co clusters to model the catalyst and run our simulat...

Research paper thumbnail of Computer Simulation Study of an SN2 Reaction in Supercritical Water

The Journal of Physical Chemistry, 1995

Research paper thumbnail of Temperature and Density Effects on an SN2 Reaction in Supercritical Water

The Journal of Physical Chemistry, 1995

Cl--water hydrogen bonds decays faster than the coordination number. By analogy to adsorption phe... more Cl--water hydrogen bonds decays faster than the coordination number. By analogy to adsorption phenomena, augmentation in the local solvent density relative to the bulk (clustering) is interpreted in three regions corresponding to gas, near-critical, and liquid-like densities: The lifetime ...

Research paper thumbnail of Molecular Dynamics Simulation of Electrolyte Solutions in Ambient and Supercritical Water. 2. Relative Acidity of HCl

The Journal of Physical Chemistry, 1996

Research paper thumbnail of Challenges in the Design of Active and Durable Alloy Nanocatalysts for Fuel Cells

Modern Aspects of Electrochemistry, 2010

Nanoparticles –from a few Angstroms to tens of nanometers- have been used as catalysts well befor... more Nanoparticles –from a few Angstroms to tens of nanometers- have been used as catalysts well before the word nanotechnology became popular. It is not surprising to expect that very small particles, having a large surface/volume ratio and a large proportion of low-coordinated sites may be much more reactive than flat surfaces. However, obtaining a uniform catalyst material, with welldefined particle

Research paper thumbnail of DFT Study of Nickel: Towards the MD Simulation of the Nickel-Water Interface

Theoretical and Computational Chemistry, 1996

ABSTRACT

Research paper thumbnail of Density functional theory: Further applications

Theoretical and Computational Chemistry, 1995

ABSTRACT

Research paper thumbnail of Theoretical Insights into the SEI Composition and Formation Mechanism: Density Functional Theory Studies

Research paper thumbnail of Ab initio and molecular dynamics studies of cation–water interactions

Research paper thumbnail of Simulation and Spectroscopy of Solvation in Water from Ambient to Supercritical Conditions

Research paper thumbnail of Density functional theory study of adsorption of OOH on Pt-based bimetallic clusters alloyed with Cr, Co, and Ni

Research paper thumbnail of Electron transfer through solid-electrolyte-interphase layers formed on Si anodes of Li-ion batteries

Electrochimica Acta, 2014

ABSTRACT

Research paper thumbnail of Atomic Resolution Single Walled Carbon Nanotube Nucleation Steps on Faceted Catalyst Particle Reveal Potential for Chirality Control

Microscopy and Microanalysis, 2014

Research paper thumbnail of Reactivity of Bimetallic Nanoclusters Toward the Oxygen Reduction in Acid Medium

Topics in Applied Physics, 2009

Research paper thumbnail of Theoritical Insights Into the Sei Composition and Formation Mechanism: Density Functional Theory Studies

Solid-Electrolyte Interphase, 2004

Research paper thumbnail of Density functional theory analysis of reactivity of PtxPdy alloy clusters

Surface Science, 2007

We investigate the reactivity of various Pt xPd y combinations (with x + y = 10 and various x: y ... more We investigate the reactivity of various Pt xPd y combinations (with x + y = 10 and various x: y ratios) towards the adsorption of specific intermediates of the oxygen reduction, using the B3PW91 hybrid density functional theory. The reactivity is shown to be not only sensitive to the composition of the cluster, but also to the atomic distribution. The calculations indicate that two different ensembles: one ordered and one randomly mixed, with overall composition Pt 3Pd 7 are thermodynamically more favorable than pure Pt 10 for the oxygen reduction reaction. The reasons for this behavior are clearly explained in terms of the atomic and electronic distribution, which makes the Pd atoms to act as electron donors both to Pt atoms and to the adsorbates, thus the reactivity of the Pd atoms in such environment becomes intermediate between Pt and Pd. Moreover, it is found that in a mixed Pt 3Pd 7 state the electronic distribution makes the average atom more similar to Pt than to Pd, whereas in an ordered Pt 3Pd 7 cluster, the average atom is more similar to Pd than to Pt.

Research paper thumbnail of Adsorption and Dissociation of H 2 O 2 on Pt and Pt-Alloy Clusters and Surfaces

J Phys Chem B, 2006

The adsorption of H(2)O(2) on Pt and Pt-M alloys, where M is Cr, Co, or Ni, is investigated using... more The adsorption of H(2)O(2) on Pt and Pt-M alloys, where M is Cr, Co, or Ni, is investigated using density functional theory. Binding energies calculated with a hybrid DFT functional (B3PW91) are in the range of -0.71 to -0.88 eV for H(2)O(2) adsorbed with one of the oxygen atoms on top Pt positions of Pt(3), Pt(2)M, and PtM(2), and enhanced values in the range of -0.81 to -1.09 eV are found on top Ni and Co sites of the Pt(2)M clusters. Adsorption on top sites of Pt(10) yields a weaker binding of -0.48 eV, whereas on periodic Pt(111) and Pt(3)Co(111) surfaces, H(2)O(2) generally dissociates into two OH radicals. On the other hand, attempts to attach H(2)O(2) on bridge sites cause spontaneous dissociation of H(2)O(2) into two adsorbed OH radicals, suggesting that stable adsorptions on bridge sites are not possible for any of the clusters or extended surfaces that are being studied. We also found that the water-H(2)O(2) interaction reduces the strength of the adsorption of H(2)O(2) on these clusters and surfaces.

Research paper thumbnail of Combined ab Initio Quantum Mechanics and Classical Molecular Dynamics Studies of Polyphosphazene Polymer Electrolytes: Competitive Solvation of Li + and LiCF 3 SO 3

Research paper thumbnail of A Density Functional Theory Study of Adsorption and Decomposition of Nitroamine Molecules on the Al(111) Surface

The Journal of Physical Chemistry C

... E-mail: kostas.termentzidis@univie.ac.at and juergen.hafner@univie.ac.at ... Details of the c... more ... E-mail: kostas.termentzidis@univie.ac.at and juergen.hafner@univie.ac.at ... Details of the calculated adsorption geometries are compiled in table 1, together with adsorption energies with respect to gas-phase Au (Eads > 0 meaning exothermic adsorption). ...

Research paper thumbnail of Yan-JPCA-110

Research paper thumbnail of 389539 Role and Stability of a Metal Carbide Catalyst in the Growth of Single-Walled Carbon Nanotubes

Achieving a high degree of selectivity in the synthesis of single-walled carbon nanotubes in a sy... more Achieving a high degree of selectivity in the synthesis of single-walled carbon nanotubes in a systematic and efficient way is one major barrier to be overcome before the exceptional properties of these materials can be exploited commercially. Many studies seem to indicate that the state and structure of the catalyst in CCVD play a fundamental role in determining structural features of the nanotubes such as chirality. Selective growth has been reported in both monometallic and carbide nanoparticles; however the contribution that either of them brings to this process has not been completely elucidated. The stability and the influence of the latter in the growing nanotube structure is the focus of this study. We determine the stability and relevant features of carbide nanoparticles and the interactions between carbide facets and the nascent carbon structure using ab initio molecular dynamics simulations. We use 55-metal-atom Ni and Co clusters to model the catalyst and run our simulat...

Research paper thumbnail of Computer Simulation Study of an SN2 Reaction in Supercritical Water

The Journal of Physical Chemistry, 1995

Research paper thumbnail of Temperature and Density Effects on an SN2 Reaction in Supercritical Water

The Journal of Physical Chemistry, 1995

Cl--water hydrogen bonds decays faster than the coordination number. By analogy to adsorption phe... more Cl--water hydrogen bonds decays faster than the coordination number. By analogy to adsorption phenomena, augmentation in the local solvent density relative to the bulk (clustering) is interpreted in three regions corresponding to gas, near-critical, and liquid-like densities: The lifetime ...

Research paper thumbnail of Molecular Dynamics Simulation of Electrolyte Solutions in Ambient and Supercritical Water. 2. Relative Acidity of HCl

The Journal of Physical Chemistry, 1996

Research paper thumbnail of Challenges in the Design of Active and Durable Alloy Nanocatalysts for Fuel Cells

Modern Aspects of Electrochemistry, 2010

Nanoparticles –from a few Angstroms to tens of nanometers- have been used as catalysts well befor... more Nanoparticles –from a few Angstroms to tens of nanometers- have been used as catalysts well before the word nanotechnology became popular. It is not surprising to expect that very small particles, having a large surface/volume ratio and a large proportion of low-coordinated sites may be much more reactive than flat surfaces. However, obtaining a uniform catalyst material, with welldefined particle

Research paper thumbnail of DFT Study of Nickel: Towards the MD Simulation of the Nickel-Water Interface

Theoretical and Computational Chemistry, 1996

ABSTRACT

Research paper thumbnail of Density functional theory: Further applications

Theoretical and Computational Chemistry, 1995

ABSTRACT

Research paper thumbnail of Theoretical Insights into the SEI Composition and Formation Mechanism: Density Functional Theory Studies

Research paper thumbnail of Ab initio and molecular dynamics studies of cation–water interactions

Research paper thumbnail of Simulation and Spectroscopy of Solvation in Water from Ambient to Supercritical Conditions

Research paper thumbnail of Density functional theory study of adsorption of OOH on Pt-based bimetallic clusters alloyed with Cr, Co, and Ni

Research paper thumbnail of Electron transfer through solid-electrolyte-interphase layers formed on Si anodes of Li-ion batteries

Electrochimica Acta, 2014

ABSTRACT

Research paper thumbnail of Atomic Resolution Single Walled Carbon Nanotube Nucleation Steps on Faceted Catalyst Particle Reveal Potential for Chirality Control

Microscopy and Microanalysis, 2014

Research paper thumbnail of Reactivity of Bimetallic Nanoclusters Toward the Oxygen Reduction in Acid Medium

Topics in Applied Physics, 2009

Research paper thumbnail of Theoritical Insights Into the Sei Composition and Formation Mechanism: Density Functional Theory Studies

Solid-Electrolyte Interphase, 2004