Cutting-edge Analysis of Surfaces and Interfaces and Its Impact in Electrochemistry
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Kyoko YOSHIOKA, Dai KATO, Tomoyuki KAMATA, Osamu NIWA
2014 Volume 82 Issue 5 Pages
322-324
Published: May 05, 2014
Released on J-STAGE: May 05, 2014
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Polycrystalline indium tin oxide (ITO) film has a rough enzyme-sized surface structure, which efficiently enhances the direct electron transfer (DET) caused by the electrocatalytic activity of cytochrome c (cyt c). It is explained that the heme iron of cyt c was sufficiently close to the polycrystalline ITO electrode to achieve DET. Polycrystalline ITO is a suitable material for the enzyme-modified electrode of an electrochemical biosensor.
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Toshihiro TAKASHIMA, Akira YAMAGUCHI, Kazuhito HASHIMOTO, Hiroshi IRIE ...
2014 Volume 82 Issue 5 Pages
325-327
Published: May 05, 2014
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The mechanism of water oxidation by MnO
2 electrodes was investigated at various pH values, using in situ UV-vis absorption spectroscopy. The surface Mn
3+ formed as an intermediate species during water oxidation showed a d-d transition band with a peak at 510 nm at pH 6, while the peak shifted to 470 nm at pH 13. This shift of the absorption peak is attributed to the deprotonation of hydroxyl ligands of Mn
3+ from OH
− to O
2−. Interrelation between the protonation state of Mn
3+ and the O
2 evolution activity of MnO
2 electrocatalysts is discussed.
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Chiaki HONDA, Shuto KIKUCHI, Tomoyuki ITO, Shinya ONODERA, Akio NAGAI, ...
2014 Volume 82 Issue 5 Pages
328-330
Published: May 05, 2014
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In this paper, an evaluation method for measuring contact resistance of aluminum current collector surfaces in energy storage systems was established. Contact resistance was calculated by a combination of chronopotentiometry and AC impedance method. Also, we found that contact resistance is dependent on current density.
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Yasufumi TAKAHASHI, Komachi ITO, Xiongwei WANG, Yoshiharu MATSUMAE, Hi ...
2014 Volume 82 Issue 5 Pages
331-334
Published: May 05, 2014
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Nanoscale cell surface topography was visualized using a scanning ion conductance microscope (SICM), where a nanopipette was used as the scanning probe to detect ionic current as feedback signal. SICM was an effective tool for noncontact topographical imaging of live cells, because measurements were performed under physiological conditions. This breakthrough technique opens up a wealth of possible new experiments in membrane and cell biology.
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Miyuki HASHIMOTO, Satoshi OKAJIMA, Toshihiro KONDO, Kenji HARA, Wang-J ...
2014 Volume 82 Issue 5 Pages
335-337
Published: May 05, 2014
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Thin film structures of [Cu
3(BTC)
2(H
2O)
3]
n (HKUST-1), which is one of Metal-organic frameworks (MOFs), prepared via step-by-step liquid phase epitaxy (LPE) method, on a TiO
2(110) surface were investigated by polarization-dependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). For the ultra thin film, PTRF-XAFS enlightened that HKUST-1 eventually formed even at 1 cycle LPE. For further growth, XRD and SEM verified well-oriented < 111 > HKUST-1 thin films on the surface. These results proposed that the adsorption structure of linkers on the surface plays an important role to control the orientation of MOF films.
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Taro UEMATSU, Yusuke KAJI, Tsukasa TORIMOTO, Susumu KUWABATA
2014 Volume 82 Issue 5 Pages
338-340
Published: May 05, 2014
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A new method to visualize electrochemical reactions by fluorescence is demonstrated by using the photoluminescence quenching of semiconductor nanoparticles which changes according to the redox states of quenchers. The photoluminescence intensity of ZnS-AgInS
2 solid solution semiconductor nanoparticles can be controlled by the electrochemical manipulation of quencher molecules. By using a fluorescence optical microscopy, the formation of Nernst diffusion layer is successfully observed as a photoluminescence intensity gradient.
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Hiroshi KONDOH, Yuki HIGASHI, Masaaki YOSHIDA, Yuji MONYA, Ryo TOYOSHI ...
2014 Volume 82 Issue 5 Pages
341-345
Published: May 05, 2014
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The structure and photo-induced charge transfer time of pyridine molecules adsorbed on a rutile TiO
2(110) surface have been studied by near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, density functional theory (DFT) calculations and core-hole-clock (CHC) spectroscopy. Polarization dependence of NEXAFS spectra and geometrical optimization by the DFT calculations revealed that the pyridine molecules are bound to the TiO
2 surface with an upright configuration where the N atom binds to a surface Ti atom. The CHC results indicate that the charge transfer from the LUMO+2 orbital of pyridine with a π* symmetry to the conduction band of TiO
2 is quite fast, where the timescale is less than 3 fs.
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Noriko UMEZAWA, Shoko SANO, Nana AOKI, Gernot FRIEDBACHER, Toshihiro K ...
2014 Volume 82 Issue 5 Pages
346-350
Published: May 05, 2014
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Flattening processes of a commercially available Au(111) single crystal surface were step-by-step investigated using atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) from a micron scale to an atomic dimension. AFM images in a micron scale showed that there were many scratches with a few nm depth on the as-received Au(111) disk surface. SEM, EDX, and XPS results indicated that there were surface contaminations such as carbon and silicon species. As a first, these contaminations could be removed by dipping the disk in concentrated H
2SO
4 and then in boiling concentrated HF. The scratches described above were disappeared after annealing by a gas flame, which is a most popular method for Au(111) single crystal preparation. After the electrochemical polishing and annealing in an electric furnace under argon atmosphere, finally, atomically flat Au(111) surfaces with dimensions of more than 500 × 500 nm
2 were obtained. With increasing of annealing period, larger terraces were obtained.
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Nagahiro HOSHI, Keita NAITO, Masashi NAKAMURA, Osami SAKATA
2014 Volume 82 Issue 5 Pages
351-354
Published: May 05, 2014
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Real surface structures of Pd(110) = 2(111)-(111) and Pd(311) = 2(100)-(111) have been determined using surface X-ray scattering (SXS) at 0.5 V (RHE) in 0.1 M HClO
4 saturated with Ar and O
2. Both surfaces have unreconstructed (1 × 1) structures. These results differ from those of Pt(110) and Pt(311) of which surfaces are reconstructed to (1 × 2) in 0.1 M HClO
4. Interlayer spacing between the first and the second layer
d12 is expanded on Pd(110) in O
2 saturated solution, whereas the spacing
d12 on Pd(311) is larger than that of the bulk in both Ar and O
2 saturated solutions.
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Masaaki YOSHIDA, Tsuyoshi IIDA, Takehiro MINEO, Takumi YOMOGIDA, Kiyof ...
2014 Volume 82 Issue 5 Pages
355-358
Published: May 05, 2014
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The electrochromic transition of a nickel borate thin film between colorless and brown was examined by means of in situ XAFS and UV/vis spectroscopy. The XAFS spectra showed that the average valence state of the nickel species in the film changed from +2.1 to +3.8 following the application of an electrode potential. Additionally, a broad peak at 700 nm was observed during in situ UV/vis absorption measurements on the application of a positive potential. These results suggest that the nickel borate film reversibly forms a NiOOH structure with a domain size of several nanometers during the electrochromic reaction.
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Takeshi HIGUCHI, Daiki MURAKAMI, Hidetoshi NISHIYAMA, Mitsuo SUGA, Ats ...
2014 Volume 82 Issue 5 Pages
359-363
Published: May 05, 2014
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Direct observation of phenomena occurring under atmospheric conditions, especially at the nanometer scale, would offer a unique opportunity to understand the dynamics of various processes. A novel electron microscope, the atmospheric scanning electron microscope (ASEM), has recently been developed and allows for the observation of nanoscale objects under atmospheric conditions. In this paper, we present some examples of dynamic phenomena in polymer materials observed using ASEM. The first example is phase separation of a binary polymer blend upon solvent evaporation, a representative example of a non-linear non-equilibrium phenomenon in physics. Phase-separated structures were found to appear at the final stage of solvent evaporation. Also, we found that irradiation of organic liquids (e.g., dibenzyl ether) with the ASEM electron beam induced polymerization, and the resulting material showed interesting cathodoluminescence behavior. Thus, ASEM may be useful as a tool for simultaneous polymerization and fabrication, in addition to offering a means for direct nanoscale observation of materials under atmospheric conditions.
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Munekazu MOTOYAMA, Makoto EJIRI, Yasutoshi IRIYAMA
2014 Volume 82 Issue 5 Pages
364-368
Published: May 05, 2014
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This paper studies the effect of current density on electrochemical Li deposition/dissolution at glassy solid electrolyte (LiPON) interfaces with a thin-film Cu current collector by in-situ scanning electron microscopy (SEM). The Li nucleation rate and the saturation density of Li nuclei increase with increasing current density. When the current density is smaller than 300 µA cm
−2, Li islands continue to separately grow under a Cu film to the critical sizes to produce small cracks in the Cu film resulting in isolated Li rod growth from the cracks. On the other hand, a current density of 1.0 mA cm
−2 provokes the nucleation of Li islands at a number of sites. They rapidly coalesce under a Cu film in all lateral directions before cracking the Cu film, whereby Li growth is prevented.
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Masaya HARA, Takahiro MIYAHARA, Takayuki HOSHI, Jiwei MA, Masanori HAR ...
2014 Volume 82 Issue 5 Pages
369-375
Published: May 05, 2014
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Proton conductive spots on the membrane surface of sulfonated poly(arylene ketone) multiblock copolymer were investigated by current-sensing atomic force microscopy (CS-AFM) under the hydrogen atmosphere with changing relative humidity, temperature, and bias voltage. The bright spots, where the hydrophilic clusters should be effectively connected inside the membrane, were distributed rather inhomogeneously on the surface at low temperature and humidity but became more homogeneous at higher temperature and humidity. The average diameter of the spots was approximately 10 nm at 40% RH, which increased to 13 nm at 70% RH. The total area of the proton conducting spots, as well as current at each spot, on the membrane surface increased at high humidity and temperature. In addition, the diameter of the proton-conductive spots and the ratio of proton-conductive area on the membrane surface continuously increased with increasing the bias voltage. This increase of the conducting area and the current should be related to the change of the bulk ionic conductivity.
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Motohiko SUZUKI, Hiroki KURIHARA, Toshiharu SAIKI
2014 Volume 82 Issue 5 Pages
376-379
Published: May 05, 2014
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Near-field fluorescence correlation spectroscopy measurements of 20 and 40 nm polystyrene nanoparticles were performed, using fiber probes with aperture diameters ranging from 100 to 250 nm. The experimental data were best fit by a two-dimensional diffusion model, implying that there was significant anisotropy associated with the movement of the particles, such that mobility normal to the wall was much lower than that parallel to the wall. Interestingly, the lateral diffusion coefficients were approximately ten times greater than predicted from the Stokes-Einstein relationship corrected by taking into account hydrodynamic drag forces due to particle-wall interactions. This discrepancy between experimental and theoretical results is possibly due to strong viscous forces as well as attractive forces at the interface.
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Takashi ICHII, Masahiro NEGAMI, Motohiko FUJIMURA, Kuniaki MURASE, Hir ...
2014 Volume 82 Issue 5 Pages
380-384
Published: May 05, 2014
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Structural analysis of the interfaces between an ionic liquid (IL) and an organic monolayer was carried out by phase modulation atomic force microscopy (PM-AFM). A quartz tuning fork sensor with a sharpened tungsten tip was used as a force sensor instead of a Si cantilever. Topographic imaging of the monolayer-covered Si(111) substrate revealed that the PM-AFM is capable of imaging the atomic steps originating from the substrate in an IL. We also carried out force curve measurement using the PM-AFM in order to directly confirm the presence of solvation layers and revealed that at least 4 layers, each with a thickness of 0.77 nm, were formed on the interface. In addition, we obtained topographic images at different driving frequencies and indicated that it is possible to image not only the sample surface but also the solvation layers formed on the IL/monolayer interface.
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Nana AOKI, Kaori SATO, Kayo HASEGAWA, Shoko SANO, Mizuki KAGEYAMA, Nor ...
2014 Volume 82 Issue 5 Pages
385-390
Published: May 05, 2014
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Self-assembly process of a porphyrin derivative [5,10,15,20-tetra-(
m-mercapto-
p-methoxyphenyl) porphyrin; TMMPP], which was designed and synthesized to be flatly adsorbed on a gold substrate surface, on a Au(111) single crystal surface was investigated by ex situ scanning tunneling microscopy (STM) and electrochemical reductive desorption measurements. A small number of TMMPP molecules were randomly but flatly adsorbed on the Au(111) surface when the deposition time was less than 1 h as the initial stage of the self-assembly process. When the deposition time was more than 20 h as the final stage of the self-assembly process, the densely-packed and flatly adsorbed TMMPP SAM formed on the Au(111) surface via a phase transition from a random to an ordered structure. These results indicated that we succeeded in the formation of the flatly adsorbed and well-defined porphyrin self-assembled monolayer (SAM) on the Au(111) surface.
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Katsuhiko NISHIYAMA, Hiroshi HARADA, Soichiro YOSHIMOTO, Taro YAMADA, ...
2014 Volume 82 Issue 5 Pages
391-395
Published: May 05, 2014
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The effect of annealing on 4-PySH and 3-PySH SAMs on Au(111) and Au(100) substrates was examined using high-resolution electron energy loss spectroscopy (HREELS) for the first time. At 300 K, the surfaces of 4- and 3-PySH SAMs on Au(111) were partially covered with artifacts. However, after annealing at the appropriate temperature, clear HREEL spectra of 4-PySH and 3-PySH SAM on Au(111) were recorded, and both the 4-PySH and 3-PySH molecules adsorbed in a flat orientation. In contrast, on Au(100), the HREEL spectra of 4-PySH and 3-PySH SAMs prepared at 300 K revealed that the pyridine rings are oriented almost perpendicular to the surface. Annealing at an appropriate temperature had a dramatic effect on the surface structure of the 4-PySH and 3-PySH SAMs: Both the 4- and 3-PySH molecules adsorbed in a flat orientation.
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Takashi ITOH, Tetsuya KAJITA, Toshiteru MAEDA, Atsuo KASUYA
2014 Volume 82 Issue 5 Pages
396-400
Published: May 05, 2014
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Water libration on a silver electrode in various alkali hydroxides (MOH, M = Li, Na, K or Cs) aqueous solutions was examined through simultaneous experiments using surface-enhanced Raman scattering (SERS) and electrochemical analysis. This technique, referred to as SERS spectroelectrochemistry, reveals the Raman spectral band between 200 and 750 cm
−1, assignable to water libration on the electrode surface, through electrode potential scanning. The Raman intensity in this spectral band changes with the electrode potential. The variation in Raman intensity of water libration observed when scanning the electrode potential is discussed in terms of water molecules at the electrode interface in various alkali hydroxide aqueous solutions.
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