Oxygen Reduction Reaction Activity of Nano-Flake Carbon-Deposited Pt 75 Ni 25 (111) Surfaces

Naoto Todoroki, Ren Sasakawa, Keisuke Kusunoki, Toshimasa Wadayama

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Oxygen reduction reaction (ORR) activity was investigated for nano-flake-like carbon-modified Pt 75 Ni 25 (111) surfaces. Surface cleaning through Ar + -sputtering and thermal annealing in an ultra-high vacuum (~ 10 −8  Pa) resulted in a Pt-enriched topmost surface, i.e., a Pt(111)-skin on Pt 75 Ni 25 (111). Arc plasma deposition (APD) of graphite under 0.08 Pa N 2 and in vacuum (~ 10 −6  Pa) generated nitrogen-doped and non-doped nano-flake-like carbon on the Pt(111)-skin surfaces, respectively. For the latter, non-doped carbon-modified Pt(111)-skin, the area-specific initial ORR activity estimated in O 2 -saturated 0.1 M HClO 4 decreased with increasing thickness of the deposited carbon. In contrast, the former, nitrogen-doped carbon with 2 and 6 Å mass-thickness enhanced the ORR activity. The Pt 4f band energies for the nitrogen-doped Pt(111)-skin were measured by X-ray photoelectron spectroscopy (XPS) and showed the chemical shift to higher biding energy (~ 0.2 eV) compared with the corresponding bands for the non-doped and Pt(111)-skin surfaces. As for the electrochemical structural stability, a specific amount of the non-doped carbon species tends to suppress the degradation of the Pt(111)-skin under applying potential cycles. The results indicate that the surface modifications by the carbon hexagonal networks of the nano-flakes could be applicable to improve ORR performance of the practical Pt-M alloy catalysts. [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)232-242
Number of pages11
JournalElectrocatalysis
Volume10
Issue number3
DOIs
Publication statusPublished - 2019 May 15

Keywords

  • Arc plasma deposition
  • Nano-flake-like carbon
  • Nitrogen-doped carbon
  • Oxygen reduction reaction
  • Pt Ni (111)
  • Pt-skin
  • Surface modification

ASJC Scopus subject areas

  • Electrochemistry

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