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<p>Manipulating surface strain via lattice mismatch can enhance electrocatalytic activity in epitaxial transition metal films, but long-term performance remains challenging. Although thick films can improve stability against dissolution, they may suffer from irreversible strain relaxation, reducing catalytic activity. Here using epitaxial platinum films for the electrochemical oxygen reduction reaction, we demonstrate thickness-dependent critical strain below which irreversible strain relaxation is avoided, defining the thicknesses range that optimizes catalyst stability and activity. First principles calculations reveal that the critical strain values range from −8.2% (compressive) to 2.7% (tensile) and the optimal strain (−2.5%) is maintained in Pt films up to ~3-nm thick. In H<sub>2</sub>–air polymer electrolyte membrane fuel cells, Pt films on iridium deliver a mass activity of 1.5 ± 0.3 A mg<sub>Pt</sub><sup>−1</sup> at 0.9 V and less than 10% performance loss after 30,000 cycles, compared with less than 0.4 A mg<sub>Pt</sub><sup>−1</sup> and more than 60% performance loss for Pt and PtNi catalysts.</p>

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Critical surface strain regime for stable and active epitaxial platinum oxygen reduction electrocatalysts

  • 期刊论文

  • 发表日期：

    2026年7月2日

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  • Zhenhua Zeng,
  • Guangdong Liu,
  • David A. Cullen,
  • Huiqiu Deng,
  • Andrew J. Steinbach,
  • Grant M. Thoma,
  • A. Jeremy Kropf,
  • Deborah J. Myers,
  • Zhongxia Shang,
  • Fumiharu Kusaka,
  • Naoto Todoroki,
  • Jeffrey P. Greeley

摘要

Manipulating surface strain via lattice mismatch can enhance electrocatalytic activity in epitaxial transition metal films, but long-term performance remains challenging. Although thick films can improve stability against dissolution, they may suffer from irreversible strain relaxation, reducing catalytic activity. Here using epitaxial platinum films for the electrochemical oxygen reduction reaction, we demonstrate thickness-dependent critical strain below which irreversible strain relaxation is avoided, defining the thicknesses range that optimizes catalyst stability and activity. First principles calculations reveal that the critical strain values range from −8.2% (compressive) to 2.7% (tensile) and the optimal strain (−2.5%) is maintained in Pt films up to ~3-nm thick. In H2–air polymer electrolyte membrane fuel cells, Pt films on iridium deliver a mass activity of 1.5 ± 0.3 A mgPt−1 at 0.9 V and less than 10% performance loss after 30,000 cycles, compared with less than 0.4 A mgPt−1 and more than 60% performance loss for Pt and PtNi catalysts.