Electrocatalysts for the anodic oxidation of borohydrides

Liu, Bin Hong; Li, Zhou Peng; Suda, S.

doi:10.1016/j.electacta.2004.02.023

Cited by 236 publications

(96 citation statements)

References 9 publications

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“…Several anode materials have been proposed to extract the 8 electrons from the BH À 4 ion [6][7][8][9] but gold is considered to be amongst the most effective [10]. The oxidation of BH À 4 ions at 100 nm sized gold nanoparticles on a gold-plated nickel grid (<0.8 mg cm À2 ) and on a commercial Au electrode (1.8-2.0 mg cm À2 ) was compared [11,12].…”

Section: Introductionmentioning

confidence: 99%

A direct borohydride–peroxide fuel cell using a Pd/Ir alloy coated microfibrous carbon cathode

León

Walsh

Patrissi

et al. 2008

Electrochemistry Communications

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a b s t r a c tA direct borohydride fuel cell with a Pd/Ir catalysed microfibrous carbon cathode and a gold-catalysed microporous carbon cloth anode is reported. The fuel and oxidant were NaBH 4 and H 2 O 2 , at concentrations within the range of 0.1-2.0 mol dm À3 and 0.05-0.45 mol dm À3 , respectively. Different combinations of these reactants were examined at 10, 25 and 42°C. At constant current density between 0 and 113 mA cm À2 , the Pd/Ir coated microfibrous carbon electrode proved more active for the reduction of peroxide ion than a platinised-carbon one. The maximum power density achieved was 78 mW cm À2 at a current density of 71 mA cm À2 and a cell voltage of 1.09 V.

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Section: Introductionmentioning

confidence: 99%

A direct borohydride–peroxide fuel cell using a Pd/Ir alloy coated microfibrous carbon cathode

León

Walsh

Patrissi

et al. 2008

Electrochemistry Communications

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“…7,34 . Though it shows activity for borohydride oxidation, the Cu electrode oxidizes at potentials near that at which borohydride is oxidized.…”

Section: Adsorption Of Bh 4 -Ions Over Close-packed Late Transition mentioning

confidence: 99%

“…Gold [1][2][3][4][5] and silver 3,6 are more selective catalysts, which could produce up to 8 electrons per borohydride molecule, however, the low activity of these catalysts limit the fuel cell efficiency and high overpotentials are required to draw sizable currents from these catalysts. Platinum, 1,[7][8] nickel, [7][8][9] and palladium 7 are more active for borohydride oxidation reactions, however an extreme activity of these catalysts for breaking B-H bonds leads to large amounts of hydrogen gas production and less than 8 e -collected per borohydride molecule converted. This lack of selectivity also limits the overall efficiency of the fuel cell.…”

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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“…where x is the number of electrons released per borohydride ion [3]. Several catalysts have been studied for the direct oxidation of borohydride ions.…”

mentioning

confidence: 99%