TY - GEN
T1 - Electrochemical stability of pt-enriched topmost surface of Ni/Pt(111) prepared by molecular beam epitaxy
AU - Todoroki, N.
AU - Iijima, Y.
AU - Takahashi, R.
AU - Yamada, Y.
AU - Matsumoto, K.
AU - Hayashi, T.
AU - Wadayama, T.
PY - 2013
Y1 - 2013
N2 - Oxygen reduction reaction (ORR) activity and stability of a molecular beam epitaxially (MBE) prepared Pt-enriched Ni0.3nm/Pt(111) surface was investigated. Reflection high-energy electron diffraction (RHEED) patterns, and a scanning tunneling microscopic (STM) image indicated that the Pt-enriched surface has long-range-ordered six-fold symmetry with atomic-scale corrugations. ORR activity was estimated by kinetically-controlled current density at 0.9 V vs. a reversible hydrogen electrode, and the as-prepared Pt-enriched surface showed 8-times-higher ORR activity than clean Pt(111). The activity steeply reduced during potential cycling between 0.6 V and 1.0 V. After 1000 potential cycles, the enhancement factor was 2.5 and a cyclic voltammetry (CV) curve exhibited an increase in EC charge for the Haddes region accompanied by the emergence of a 0.13 V redox feature caused by (110) surface defects. These results suggest that the electrochemical stability of the underlying Ni atoms determines the durability of Pt-Ni alloy catalysts.
AB - Oxygen reduction reaction (ORR) activity and stability of a molecular beam epitaxially (MBE) prepared Pt-enriched Ni0.3nm/Pt(111) surface was investigated. Reflection high-energy electron diffraction (RHEED) patterns, and a scanning tunneling microscopic (STM) image indicated that the Pt-enriched surface has long-range-ordered six-fold symmetry with atomic-scale corrugations. ORR activity was estimated by kinetically-controlled current density at 0.9 V vs. a reversible hydrogen electrode, and the as-prepared Pt-enriched surface showed 8-times-higher ORR activity than clean Pt(111). The activity steeply reduced during potential cycling between 0.6 V and 1.0 V. After 1000 potential cycles, the enhancement factor was 2.5 and a cyclic voltammetry (CV) curve exhibited an increase in EC charge for the Haddes region accompanied by the emergence of a 0.13 V redox feature caused by (110) surface defects. These results suggest that the electrochemical stability of the underlying Ni atoms determines the durability of Pt-Ni alloy catalysts.
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U2 - 10.1149/05002.1707ecst
DO - 10.1149/05002.1707ecst
M3 - Conference contribution
AN - SCOPUS:84885722510
SN - 9781607683506
T3 - ECS Transactions
SP - 1707
EP - 1713
BT - Polymer Electrolyte Fuel Cells 12, PEFC 2012
PB - Electrochemical Society Inc.
T2 - 12th Polymer Electrolyte Fuel Cell Symposium, PEFC 2012 - 222nd ECS Meeting
Y2 - 7 October 2012 through 12 October 2012
ER -