Electrochemical and spectroscopic study of novel Cu and Fe-based catalysts for oxygen reduction in alkaline media

Qinggang He, Xiaofang Yang, Ruihua He, Agustín Bueno-López, Hamish Miller, Xiaoming Ren, Wanli Yang, Bruce E. Koel

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

We synthesized two "single-core" Fe-N x/C and Cu-N x/C electrocatalysts and a bi-core CuFe-N x/C composite electrocatalyst using iron and copper phthalocyanine-based precursors and a high-temperature pyrolysis method. The morphology, structure, and activity toward the oxygen reduction reaction (ORR) in alkaline media were evaluated for each electrocatalyst by transmission electron microscopy (TEM), X-ray Diffraction (XRD), and the rotating ring-disk electrode (RRDE) method. Although the Cu-N x/C catalyst showed lower catalytic activity than Fe-N x/C, the presence of Cu enhanced the ORR performance of bi-core CuFe-N x/C, as compared to single-core Fe-N x/C. To fully understand the synergistic effect between Cu and Fe on this enhancement, high resolution X-ray photoelectron spectroscopy (HR-XPS) and soft X-ray absorption spectroscopy (XAS) was employed to study the electronic structure of as-synthesized electrocatalysts. The HR-XPS analysis showed that metal-nitrogen bonding was maintained and that the oxidation states of Fe and Cu were influenced by the presence of the second metal in the bi-core catalyst. The XAS data revealed that a fraction of an electron was transferred from Fe to Cu, which may help to lower the kinetic barrier during the ORR process. Based on our experimental results and four different models, we briefly discuss ORR mechanisms on these metallic catalysts.

Original languageEnglish (US)
Pages (from-to)169-179
Number of pages11
JournalJournal of Power Sources
Volume213
DOIs
StatePublished - Sep 1 2012

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

Keywords

  • Alkaline fuel cell
  • Cu
  • Fe
  • Non-noble electrocatalyst
  • Oxygen reduction reaction
  • X-ray absorption spectroscopy

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