Evaluation of the Electrochemical Stability of Model Cu-Pt(111) Near-Surface Alloy Catalysts

Jakub Tymoczko, Federico Calle-Vallejo, Viktor Čolić, Wolfgang Schuhmann, Aliaksandr S. Bandarenka

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Better understanding of the factors responsible for the long-term stability of electrocatalysts is of increasing importance for the development of new generations of efficient electrode materials relevant for sustainable energy provision. Therefore, experiments with model, often single-crystal catalytic surfaces are of significance for fundamental electrochemistry and technological applications. Among model electrocatalysts, near-surface alloys (NSAs) of Pt with Cu, Ni and other metals formed via electrochemical deposition and thermal annealing have shown remarkable properties, demonstrating high activity towards a number of important reactions, including the oxygen reduction reaction (ORR) and CO oxidation. However, relatively little is known about the electrochemical stability and mechanisms of degradation of model NSAs. In this work, we employ a simple electrochemical approach, supported by density functional theory calculations, to evaluate the stability of Cu-Pt(111) NSAs in 0.1 M HClO4. Our results show that ∼30% of the Cu atoms initially incorporated into the second atomic layer of Pt are lost within the first 2000 cycles performed between 0.05 V and 1.0 V (RHE). After 5000 cycles, ca. half of the Cu atoms initially placed in the second atomic layer still remained in the subsurface region. The dissolution of Cu has a substantial impact on the measured shift in the average OH-binding energy for the catalyst surface and, consequently, on the ORR activity. Interestingly, after dissolution of Cu from NSAs, voltammetric features, which are characteristic to the Pt(111) facets, are partially restored suggesting the formation of NSA and Pt(111) domains in the resulting surface.

Original languageEnglish
Pages (from-to)469-474
Number of pages6
JournalElectrochimica Acta
Volume179
DOIs
StatePublished - 10 Oct 2015

Keywords

  • Electrocatalysis
  • Electrochemical interface
  • Stability, Cu-Pt(111) near-surface alloys

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