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Harada M, Noguchi H, Zanetakis N, Takakusagi S, Song W, Uosaki K. Construction of multilayers of bare and Pd modified gold nanoclusters and their electrocatalytic properties for oxygen reduction. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2011; 12:044606. [PMID: 27877414 PMCID: PMC5090492 DOI: 10.1088/1468-6996/12/4/044606] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 07/07/2011] [Accepted: 04/17/2011] [Indexed: 05/30/2023]
Abstract
Multilayers of gold nanoclusters (GNCs) coated with a thin Pd layer were constructed using GNCs modified with self-assembled monolayers (SAMs) of mercaptoundecanoic acid and a polyallylamine hydrochloride (PAH) multilayer assembly, which has been reported to act as a three-dimensional electrode. SAMs were removed from GNCs by electrochemical anodic decomposition and then a small amount of Pd was electrochemically deposited on the GNCs. The kinetics of the oxygen reduction reaction (ORR) on the Pd modified GNC/PAH multilayer assembly was studied using a rotating disk electrode, and a significant increase in the ORR rate was observed after Pd deposition. Electrocatalytic activities in alkaline and acidic solutions were compared both for the GNC multilayer electrode and Pd modified GNC electrode.
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Affiliation(s)
- Motoko Harada
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Hidenori Noguchi
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
- International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
- Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
| | - Nikolas Zanetakis
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Satoru Takakusagi
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
- Present address: Catalysis Ressearch Center, Hokkaido University, Sapporo 001-0021, Japan
| | - Wenbo Song
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
- Present address: College of Chemistry, Jilin University, Changchun 130012, China
| | - Kohei Uosaki
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
- International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
- Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
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Yagi I, Idojiri S, Awatani T, Uosaki K. Electrodeposition of flattened Cu nanoclusters on a p-GaAs(001) electrode monitored by in situ optical second harmonic generation. J Phys Chem B 2007; 109:5021-32. [PMID: 16863162 DOI: 10.1021/jp045458s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In situ optical second harmonic generation (SHG) technique was employed to investigate the shape and density of Cu nanoclusters, which were electrochemically formed on p-GaAs(001) electrode surfaces. Since GaAs is not a centrosymmetric medium, a significant portion of SHG signal arises from the bulk dipole susceptibility, but it was possible to separate a surface-induced signal from a bulk-induced signal by choosing an appropriate experimental geometry and appropriate data processing. The rotational anisotropy (RA) pattern of the SHG signal from a p-GaAs(001) electrode changed in both shape and magnitude during potential cycling in an electrolyte solution containing Cu2+. The surface plasmon-induced SHG signal from Cu nanoclusters deposited on GaAs was attributed to the modulation source for the RA-SHG pattern. More detailed study was carried out with both in situ SHG and ex situ AFM measurements for Cu nanoclusters deposited by potential step. The results showed that the SHG signal at the present optical geometry was sensitive to the number of oblate or flattened Cu nanoclusters with lateral diameter larger than 30 nm and that the SHG enhancement occurred because of resonant coupling between the surface plasmon induced in the flattened Cu nanoclusters and the near-infrared fundamental light.
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Affiliation(s)
- Ichizo Yagi
- Physical Chemistry Laboratory, Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
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Yagi I, Chiba M, Uosaki K. Optical Recognition of Surface Chirality at Au(hkl) Single Crystalline Surfaces by Second Harmonic Generation Rotational Anisotropy. J Am Chem Soc 2005; 127:12743-6. [PMID: 16144425 DOI: 10.1021/ja053724p] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Two-dimensional chirality at naturally chiral gold single crystalline surfaces was detected and characterized using optical second harmonic generation (SHG) measurements. SHG rotational anisotropy (SH-RA) patterns at Au(643)S and Au(643)R surfaces were mirror symmetric to each other. Systematic SH-RA measurements at chiral Au(hkl) surfaces with the same step and kink structures but different (111) terrace widths showed a linear correlation between surface step density and SH-RA fitting parameters arising from defects. These results indicate that SH-RA measurements provide information not only on surface chirality but also on density of surface defects.
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Affiliation(s)
- Ichizo Yagi
- Physical Chemistry Laboratory, Division of Chemistry, Graduate School of Science, Hokkaido University, N10W8 Kita-ku, Sapporo 060-0810, Japan.
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