First principles mechanistic study of borohydride oxidation over the Pt(111) surface

Rostamikia, Gholamreza; Janik, Michael J.

doi:10.1016/j.electacta.2009.10.002

Cited by 68 publications

(104 citation statements)

References 50 publications

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“…PdeIr(111) is therefore, active towards this initial oxidation step at more negative potentials than Au(111). The borohydride adsorption energy on Pt(111) was À1.85 eV, at À0.5 V vs. SHE, which causes dissociation to BH * þ 3H * [14]. The free energies of the electro-oxidation steps that involve the surface species can be calculated using the following equation:…”

Section: Dft Calculation Results and Discussionmentioning

confidence: 99%

“…The relative energy of each species was calculated by combining Equations (7) or (8) and (12), leading to Equation (13) [14].…”

Section: Dft Calculation Results and Discussionmentioning

confidence: 99%

“…The harmonic vibrational modes were calculated to determine the zero point vibrational (ZPVE) corrections to the total energy of adsorbates. [14], who calculated those values by adding ZPVE, pressure volume (PV) and entropic terms to the isolated gas phase molecule energy (E DFT ). Experimental solvation free energies and concentration adjustments were included to consider solution conditions, assuming an ideal solution.…”

Section: Methodsmentioning

confidence: 99%

“…The optimum reaction path was obtained by investigating the elementary surface reaction energies and postulating the lowest energy path taking into account the activation energy for each electron transferred. As a first approximation, the energy of a transferred electron and the ion adsorption energies were made linearly dependent on the electrochemical potential and the energy of the adsorbed species was calculated as their free energy [14,17,26]. All calculations were performed using the ab initio total energy and molecular-dynamics Vienna ab initio simulation program (VASP) developed at the Institute for Material Physics at the University of Vienna [27e29].…”

Section: Methodsmentioning

confidence: 99%

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Pd–Ir alloy as an anode material for borohydride oxidation

Merino-Jiménez

Janik

León

et al. 2014

Journal of Power Sources

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Section: Dft Calculation Results and Discussionmentioning

confidence: 99%

“…The relative energy of each species was calculated by combining Equations (7) or (8) and (12), leading to Equation (13) [14].…”

Section: Dft Calculation Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Pd–Ir alloy as an anode material for borohydride oxidation

Merino-Jiménez

Janik

León

et al. 2014

Journal of Power Sources

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“…We have previously applied density functional theory (DFT) methods to evaluate the borohydride oxidation mechanism over the Au(111) [10][11] and Pt(111) surfaces, 12 as well as Pd-Ir alloys. 13 Our mechanistic studies [10][11] of the BOR over the Au(111) surface concluded that the unfavorable borohydride adsorption and low activity for breaking B-H bonds causes low activity and large overpotentials.…”

Section: Introductionmentioning

confidence: 99%

Electrocatalyst Design for Direct Borohydride Oxidation Guided by First Principles

Rostamikia¹,

Patel²,

Merino-Jiménez

et al. 2017

J. Phys. Chem. C

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Density functional theory (DFT) calculations are used to propose a Au–Cu binary metal catalyst for the electrochemical borohydride oxidation reaction (BOR), which is evaluated experimentally and observed to show enhanced oxidation activity relative to a pure Au electrode. Our previous work has applied DFT methods to determine the BOR mechanism and elucidate the key reaction steps that dictate catalyst activity and selectivity to complete oxidation. A balanced initial adsorption strength of the borohydride anion is essential for an active and selective catalyst. Adsorption must be strong enough to provide a reasonable coverage of surface species and promote B–H bond dissociation but not so strong as to promote easy dissociation and provide a high coverage of surface H atoms that result in H2 evolution. Borohydride adsorption energetics were evaluated for a series of close-packed pure metal surfaces. Copper catalysts appear encouraging but are not electrochemically stable under reaction conditions. Gold–copper alloys are predicted to show increased activity compared to a pure gold electrode while maintaining the selectivity to direct oxidation and increasing the stability compared to pure Cu. DFT results suggest an approximately 0.2 V decrease in the overpotential for borohydride oxidation on a Au2Cu(111) electrode compared to that on a Au(111) electrode. This DFT-predicted reduction in overpotential is realized experimentally. Electrodeposition was used to prepare AuCu electrodes, and their borohydride oxidation electrokinetics were examined by linear sweep voltammetry. An 88.5% gold and 11.5% copper sample demonstrated an overpotential reduction of 0.17 V compared to a pure Au electrode. The binding energy and adsorption free energy of BH4 – over other surface alloys are also examined to further identify promising BOR electrodes.

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