Pd-Ir alloy as an anode material for borohydride oxidation

Merino-Jimenez, I.; Janik, M. J.; Ponce De Leon, C.; Walsh, F. C.

Abstract

A Pd-Ir alloy (1:1) coated on microfibrous carbon (11 μm diameter) supported on a titanium plate was evaluated as an electrode for the anodic oxidation of borohydride. The hydrogen generated, due to the parallel reaction of borohydride hydrolysis, was measured during the electrolysis obtaining less than 0.1 cm 3 min -1 H 2 between -1 and 0 V vs. Hg/HgO (-0.86 and 0.14 V vs. SHE), while the current densities for the oxidation of borohydride were up to 367 mA cm -2 in 0.5 mol dm -3 NaBH 4 + 3 mol dm -3 NaOH. The low rate of hydrogen generation suggests that Pd-Ir could be a promising catalyst for borohydride oxidation. However, higher rates of hydrogen were generated at the open circuit potential, which is inconvenient in the direct borohydride fuel cell. Cyclic voltammetry allowed analysis of the oxidation peaks due to the borohydride oxidation. To obtain a further understanding of the borohydride oxidation mechanism at Pd-Ir electrodes, density functional theory (DFT) was used to examine the reaction mechanism at Pd 2 -Ir 1 (111) and Pd 2 -Ir 2 (111) surfaces. The competition between borohydride oxidation and hydrogen evolution on the Pd-Ir alloys is compared with that on pure Pd(111), suggesting that the presence of Ir favors borohydride oxidation rather than hydrogen evolution. © 2014 Elsevier B.V. All rights reserved.

Citation

Merino-Jimenez, I., Janik, M. J., Ponce De Leon, C., & Walsh, F. C. (2014). Pd-Ir alloy as an anode material for borohydride oxidation. Journal of Power Sources, 269, 498-508. https://doi.org/10.1016/j.jpowsour.2014.06.140

• Journal Article Type: Article
• Acceptance Date: Jun 25, 2014
• Publication Date: Dec 10, 2014
• Journal: Journal of Power Sources
• Print ISSN: 0378-7753
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 269
• Pages: 498-508
• DOI: https://doi.org/10.1016/j.jpowsour.2014.06.140
• Keywords: borohydride oxidation, DBFC, hydrolysis of borohydride, DFT, electrocatalysis
• Public URL: https://uwe-repository.worktribe.com/output/825630
• Publisher URL: http://dx.doi.org/10.1016/j.jpowsour.2014.06.140