The degradation of Pt/IrOx oxygen bifunctional catalysts

da Silva GC, Mayrhofer K, Ticianelli EA, Cherevko S (2019)

Publication Type: Journal article

Publication year: 2019

Journal

Electrochimica Acta Elsevier

Book Volume: 308

Pages Range: 400-409

DOI: 10.1016/j.electacta.2019.04.017

Abstract

Platinum and iridium mixtures or alloys are the state-of-the-art bifunctional oxygen catalysts for unitized regenerative fuel cells (URFCs). Recently, we have shown that the degradation of these catalysts represents a serious challenge. In this work we explore the degradation mechanisms further by considering different catalysts and experimental conditions. For this, Pt/IrO x with varying Pt to Ir ratios are synthesized and their performances are evaluated. It is found that catalysts with higher Pt and Ir contents have higher oxygen reduction (ORR) and evolution reaction (OER) activities, respectively. The materials stability is investigated under a potential pulses protocol. Using on-line dissolution analysis, it is found that, besides the transient Pt dissolution identified in the previous works, continuous dissolution of Ir during the OER must be considered. The latter is assigned to a continuous formation of common OER and Ir dissolution intermediates. Further, identical location microscopy is employed to reveal the changes in the catalyst layer structure and morphology. It is shown that dissolution triggers significant particles agglomeration/coalescence, which are the main causes for the catalysts degradation. These processes must be attenuated for a feasible long-term application of Pt/IrO x materials as bifunctional oxygen catalyst.

Authors with CRIS profile

Karl Mayrhofer Lehrstuhl für Elektrokatalyse (HIERN)

Involved external institutions

University of Groningen / Rijksuniversiteit Groningen NL Netherlands (NL)

How to cite

APA:

da Silva, G.C., Mayrhofer, K., Ticianelli, E.A., & Cherevko, S. (2019). The degradation of Pt/IrOx oxygen bifunctional catalysts. Electrochimica Acta, 308, 400-409. https://dx.doi.org/10.1016/j.electacta.2019.04.017

MLA:

da Silva, Gabriel C., et al. "The degradation of Pt/IrOx oxygen bifunctional catalysts." Electrochimica Acta 308 (2019): 400-409.

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