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Volume 84 , Issue 3
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Preface
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  • Morio CHIWATA, Hiroshi YANO, Satoshi OGAWA, Masahiro WATANABE, Akihiro ...
    Volume 84 (2016) Issue 3 Pages 133-137
    Released: March 05, 2016
    JOURNALS OPEN ACCESS
    We have prepared carbon-supported Pt-M (M = Fe, Co, and Ni) alloy nanoparticles with uniform size and composition as cathode catalysts for polymer electrolyte fuel cells. In order to protect the underlying Pt-M alloy from dealloying and maintain high mass activity for the oxygen reduction reaction (ORR), two atomic layers of Pt-skin (Pt2AL) were formed on the Pt-M nanopartcicles. By means of various types of analysis, including X-ray diffraction (XRD), inductively coupled plasma mass analysis (ICP-MS), thermogravimetry (TG), and transmission electron microscopy (TEM), the formation of monodisperse Pt2AL–Pt-M/C was confirmed. The kinetically-controlled ORR activities (mass activity, MAk, and area-specific activity, jk) for the ORR at Nafion®-coated Pt2AL–Pt-M/C catalysts in O2-saturated 0.1 M HClO4 solution were evaluated by the use of a multi-channel flow double electrode cell at 65°C. It was found that the initial value of MAk at Pt2AL–PtNi/C was the highest, i.e., 3.3 times higher than that at a commercial catalyst, carbon-supported Pt (c-Pt/C). In contrast, the Pt2AL–PtCo/C catalyst exhibited superior durability, so that dealloying was almost entirely suppressed, together with a great mitigation of the particle agglomeration after applying 104 cycles of potential steps between 0.6 V and 1.0 V.
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  • Alireza MOHADESI, Somayeh PARVARESH, Zarrin ESHAGHI, Mohammad Ali KARI ...
    Volume 84 (2016) Issue 3 Pages 138-142
    Released: March 05, 2016
    JOURNALS OPEN ACCESS
    In this study, we have demonstrated that 4-aminohippuric acid (AHA) can be coupled to acid-treated multiwalled carbon nanotubes (MWNTs) in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) and assembled as AHA-MWNT composites. These functionalized MWNTs can be used for modification of glassy carbon electrode and applied for determination of copper(II) ions. The electrochemical method was based on preconcentration of copper ions onto an electrode surface and then their anodic stripping voltammetric determination. The analytical curve for Cu(II) ions covered the linear range varying from 1.0 up to 230.0 µg L−1. The limit of detection was found to be 0.4 µg L−1, while the relative standard deviation at 5.0 and 200.0 µg L−1 were 1.5 and 1.1%, respectively. Most of the coexisting ions had little or no effect on the determination of copper(II). The obtained results suggest that the proposed method can be applied as a simple and efficient alternative way for the determination of copper ions which have good accuracy in real samples such as human hair and natural waters.
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  • Dongdong PENG, Junsheng WU, Lijuan CHANG, Kun PANG, Xiaogang LI
    Volume 84 (2016) Issue 3 Pages 143-150
    Released: March 05, 2016
    JOURNALS OPEN ACCESS
    A serial of composite coatings produced by combination of cerium sol-gel coatings and cerium conversion layers has been developed in this work: (1) sol-gel coating sealed by conversion coating; (2) sol-gel coating sealed by low-density sol; (3) conversion coating thickened by sol-gel coating. For both sol-gel coatings and conversion coatings, cerium chloride heptahydrate (CeCl3·7H2O) was used as cerium source. In order to evaluate the anti-corrosion properties of these composite coatings, Electrochemical Impedance Spectroscopy (EIS) and salt spray test (SST) were employed as the assessing method. Furthermore, the surface morphology of these composite coatings was characterized by SEM observation. The EIS and SST results thus obtained showed that the anti-corrosion properties of the composite coating (1) had been remarkably improved compared to the any single layer of sol-gel coating or conversion coating. Furthermore, the SEM observation revealed that the morphology of that composite coating was uniform and homogeneous, which may explicate the superior corrosion-resistant performance obtained by the composite coating (1). By contrast, other composite coatings including composite coating (2) and (3) were not as good as composite coating (1) in corrosion resistance, which could be attributed to cracks and heterogeneous microstructure existing on the surface of these composite coatings.
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  • Takashi INAMI, Kunihiro TAMAHASHI, Takashi NAMEKAWA, Akio CHIBA, Jin O ...
    Volume 84 (2016) Issue 3 Pages 151-155
    Released: March 05, 2016
    JOURNALS OPEN ACCESS
    Crystal grain sizes less than 40 nm diameter, i.e., mean free path of an electron in Cu, in both the upper and bottom part of Cu interconnects with 70 nm width and 150 nm depth as a function of overburden Cu plated films with 150 nm, 300 nm and 450 nm thickness have been evaluated by X-ray diffraction method. In the upper part of the Cu interconnects, the frequency ratio of the crystal grains with less than 40 nm diameter was quite small and changed little in the Cu interconnects among overburden Cu films with different thickness. In the bottom part of the Cu interconnect, however, the frequency ratio of the crystal grain with less than 40 nm diameter was found to be very dependent on the thickness of overburden Cu films. The frequency ratio was about 20% at the overburden Cu film thickness of 150 nm, while the frequency ratio decreased to less than 2% at the overburden Cu film thickness of 450 nm. The resistivity of narrow Cu interconnects was found to increase with the increase of the frequency ratio of crystal grains less than 40 nm diameter at the bottom part of Cu interconnects.
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