TY - JOUR
T1 - Microscopic surface structures and ORR activities for vacuum-deposited Pt/Ni/Pt(1 1 1) and Pt/Ni/Pt(1 1 0) sandwich structures
AU - Todoroki, N.
AU - Dasai, T.
AU - Asakimori, Y.
AU - Wadayama, T.
N1 - Funding Information:
This study was supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan.
PY - 2014/6/15
Y1 - 2014/6/15
N2 - Pt0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 1) and Pt 0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 0) atomic sandwich structures were prepared through alternating vacuum depositions of Ni followed by Pt onto clean Pt(1 1 1) and (1 1 0) substrates at room temperature under ultra-high-vacuum (UHV) conditions. After the samples were transferred from UHV to a 1-atm N2 atmosphere, their oxygen reduction reaction (ORR) activities were evaluated in O2-saturated 0.1 M HClO4 at 0.9 V vs. reversible hydrogen electrode. Pt0.6nm/Ni 0.6nm/Pt(1 1 1) and Pt0.6nm/Ni0.6nm/Pt(1 1 0) were most active among the respective Pt/Ni/Pt(1 1 1) and Pt/Ni/Pt(1 1 0) sandwich series: the activities of the former and latter sandwich structures were approximately five- and threefold greater than those of the corresponding clean Pt(1 1 1) and (1 1 0) substrate surfaces. Scanning tunneling microscopy images of the as-prepared Pt0.6nm/Ni0.6nm/Pt(1 1 1) and Pt0.6nm/Ni0.6nm/Pt(1 1 0) surfaces revealed three-dimensionally grown hexagonal-shaped small domains of Pt(1 1 1) (approximately 2 nm in size) and parallelogram-shape (1 1 0) terrace islands oriented along 〈1 1 0〉, respectively. The results indicate that not only the atomic arrangements of the topmost Pt layers but also the nanoscale morphologies of Pt-Ni in the surface vicinities determine the enhancement of the ORR activity of Pt-M alloy catalysts.
AB - Pt0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 1) and Pt 0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 0) atomic sandwich structures were prepared through alternating vacuum depositions of Ni followed by Pt onto clean Pt(1 1 1) and (1 1 0) substrates at room temperature under ultra-high-vacuum (UHV) conditions. After the samples were transferred from UHV to a 1-atm N2 atmosphere, their oxygen reduction reaction (ORR) activities were evaluated in O2-saturated 0.1 M HClO4 at 0.9 V vs. reversible hydrogen electrode. Pt0.6nm/Ni 0.6nm/Pt(1 1 1) and Pt0.6nm/Ni0.6nm/Pt(1 1 0) were most active among the respective Pt/Ni/Pt(1 1 1) and Pt/Ni/Pt(1 1 0) sandwich series: the activities of the former and latter sandwich structures were approximately five- and threefold greater than those of the corresponding clean Pt(1 1 1) and (1 1 0) substrate surfaces. Scanning tunneling microscopy images of the as-prepared Pt0.6nm/Ni0.6nm/Pt(1 1 1) and Pt0.6nm/Ni0.6nm/Pt(1 1 0) surfaces revealed three-dimensionally grown hexagonal-shaped small domains of Pt(1 1 1) (approximately 2 nm in size) and parallelogram-shape (1 1 0) terrace islands oriented along 〈1 1 0〉, respectively. The results indicate that not only the atomic arrangements of the topmost Pt layers but also the nanoscale morphologies of Pt-Ni in the surface vicinities determine the enhancement of the ORR activity of Pt-M alloy catalysts.
KW - Low-energy electron diffraction
KW - Molecular beam epitaxy
KW - Oxygen reduction reaction
KW - Platinum-based alloys
KW - Polymer electrolyte membrane fuel cell
KW - Scanning tunneling microscopy
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U2 - 10.1016/j.jelechem.2014.04.008
DO - 10.1016/j.jelechem.2014.04.008
M3 - Article
AN - SCOPUS:84899817804
SN - 1572-6657
VL - 724
SP - 15
EP - 20
JO - Journal of Electroanalytical Chemistry
JF - Journal of Electroanalytical Chemistry
ER -