First-principles based microkinetic modeling of borohydride oxidation on a Au(111) electrode

Rostamikia, Gholamreza; Mendoza, Alfonso J.; Hickner, Michael A.; Janik, Michael J.

doi:10.1016/j.jpowsour.2011.07.042

Cited by 100 publications

(99 citation statements)

References 28 publications

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“…The reaction energy and activation energy for each step of the oxidation of borohydride were calculated using the lowest energy adsorbed states [15,16]. The harmonic vibrational modes were calculated to determine the zero point vibrational (ZPVE) corrections to the total energy of adsorbates.…”

Section: Methodsmentioning

confidence: 99%

“…Experimental solvation free energies and concentration adjustments were included to consider solution conditions, assuming an ideal solution. The activation energy for each step of the borohydride oxidation reaction on PdeIr surfaces was calculated by locating transition states between the lowest energy adsorbed states, presuming that each step follows the minimum energy path [15,16]. The transition states of elementary reactions on the surfaces were isolated with the climbing image nudged elastic band method (CI-NEB) [34], which finds saddle points and minimum energy paths between the known reactants and products.…”

Section: Methodsmentioning

confidence: 99%

“…The linear free energy, computational hydrogen electrode method is used to determine potential dependent reaction energies [17]. Potential dependent activation barriers for elementary reaction steps are determined using an approach recently developed in the Janik group [16,18]. The effect of the Ir content of in the PdeIr alloy is also analyzed by considering reaction energetics on Pd 2 Ir 1 (111) and Pd 2 Ir 2 (111) surfaces.…”

Section: à3mentioning

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: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: à3mentioning

confidence: 99%

See 1 more Smart Citation

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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“…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. Alternatively, very exothermic, dissociative adsorption of BH 4 -ions over the platinum surface produces a large surface coverage of hydrogen.…”

Section: Introductionmentioning

confidence: 95%

“…For the Au(111) surface, we previously determined U 0 and a  value that allowed a DFT-based microkinetic model to match experimental kinetics, 11 such that…”

Section: Potential Dependence Of Activation Barriersmentioning

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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