Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
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Volume 83 , Issue 5
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Functionality and Application of Carbon Materials
Visions
Headline
  • Jun-ichi OZAKI, Yasuo IMASHIRO
    Volume 83 (2015) Issue 5 Pages 319-325
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    The launch of the fuel cell vehicle (FCV) in December 2014 has moved our society into the era of hydrogen energy. Expectations for, and demands on, this technology will first increase steadily and then explosively. Owing to the scarcity of available natural resources and considering costs, the development of cathodes using non-platinum catalysts is an important issue to be addressed for the stable and secure provision of FCVs. We have been developing carbon alloy catalysts, such as nanoshell-containing carbon and boron nitrogen (BN)-doped carbon catalysts, where catalytic activities originate from the carbon surface and not from surface metal complexes. First, we discuss the discovery of carbon materials exhibiting electrocatalytic activity followed by their application to ORR. Second, we provide experimental evidence for ORR activity originating from warped graphitic layers. Next, we describe useful methods to obtain highly active carbon alloy catalysts. Finally, we report a notable single cell performance of 0.65 W/cm2 using air as the oxidant.
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Communications
Articles
  • Wulan Tri WAHYUNI, Tribidasari A. IVANDINI, Prastika K. JIWANTI, Endan ...
    Volume 83 (2015) Issue 5 Pages 357-362
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    This study emphasizes the electrochemical detection of Neuraminidase (NA) based on NA inhibition by Zanamivir. The detection method was developed based on the difference of electrochemical responses of Zanamivir in the presence and the absence of NA in phosphate buffer solution (pH 5.5). Gold and gold-modified boron-doped diamond was used as the working electrode and the measurement was conducted using cyclic voltammetry method. A linear calibration curve of Zanamivir was observed in the concentration range of 5 × 10−6–1 × 10−4 mol/L (R2 = 0.991), with the estimated limit of detection (LOD) of 1.49 × 10−6 mol/L. The presence of NA increases the peak current of gold oxidation and reduction with linear calibration curves were monitored in the concentration range of 0–15 mU (R2 = 0.996). An estimated LOD of 0.25 mU NA and an excellent reproducibility of the detection with an RSD of 1.18% can be achieved. Application of a real sample was successfully demonstrated for NA detection in the presence of mucin, suggested that the method is promising for pharmaceutical or medical application.
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  • Akira KOTANI, Kota NAGAMI, Chika MINO, Yasuhito SUGAWARA, Kouji TAKAHA ...
    Volume 83 (2015) Issue 5 Pages 363-367
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    Voltammetric detection using a boron doped diamond (BDD) electrode coupled with capillary liquid chromatography (CLC) was developed for determining nobiletin, one of the polymethoxyflavones (PMFs), in plasma samples. CLC with electrochemical detection (CLC-ECD) was performed using a capillary octadecylsilica (ODS) column, water-acetonitrile-phosphoric acid (65:35:0.5, v/v/v), as a mobile phase, and an applied potential at +1.45 V vs. Ag/AgCl. Chromatographic peak heights were found linearly related to the amounts of nobiletin injected from 0.48 pg to 0.40 ng (r = 0.999). The detection limit (S/N = 3) was 0.13 pg. The concentrations of nobiletin in rat plasma after oral ingestion of 5.0 mL kg−1 Citrus depressa juice, corresponding to 0.17 mg kg−1 nobiletin, were determined to obtain a concentration-time profile of nobiletin by the present CLC-ECD method, which required only 30 µL of plasma sample for each time point. Based on the concentration-time profile of nobiletin in the rat plasma, the pharmacokinetic parameters of maximum drug concentration (Cmax), maximum drug concentration time (tmax), and area under the concentration-time curve (AUC0-3 h) were obtained.
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  • Mitsuhiro INOUE, Kazuhiro NAGAI, Sayoko SHIRONITA, Takayuki ABE, Minor ...
    Volume 83 (2015) Issue 5 Pages 368-371
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    A carbon with Pt (C–Pt) catalyst was prepared by a co-sputtering technique. Pt4f peaks of the prepared sample were observed at higher binding energies than those of a Pt sputtered sample. These Pt4f peaks shifted to the low binding energies with an increase in a post-annealing temperature, whereas the C1s peak position was unchanged. For the C–Pt catalyst as sputter-deposited, the methanol oxidation performance was enhanced by the presence of O2. This O2-enhnaced methanol oxidation was suppressed by the post-annealing at 160°C, while the reaction selectivity of the methanol oxidation was retained.
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  • Hiroto FUNABASHI, Kazuki MURATA, Seiya TSUJIMURA
    Volume 83 (2015) Issue 5 Pages 372-375
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    MgO-templated porous carbon (MgOC) was developed for D-fructose dehydrogenase (FDH) electrodes. MgOCs with an average pore diameter ranging from 10 to 100 nm were used in this study. FDH adsorbed on a MgOC electrode exhibited significant catalytic currents for D-fructose-oxidation without a redox mediator. When the pore size of MgOC was much larger than the size of FDH, a sufficient amount of FDH was adsorbed in the mesopore on and even inside the MgOC structure. In contrast, when the pore size of MgOC was comparable to the size of FDH, the catalytic current depended only on the amount of enzyme adsorbed in mesopores formed at the surface of the carbon particles; however, an enhanced thermal stability of FDH was observed. Thus, FDH was stabilized through encaging in carbon mesopores with a size comparable to that of the enzyme.
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  • Misako OHTSUKA, Fusao KITAMURA
    Volume 83 (2015) Issue 5 Pages 376-380
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    The redox reaction of iron phthalocyanine (FePc) combined with electrochemically-reduced graphene oxide (ER-GO) was investigated as a function of FePc fraction. A FePc/ER-GO/GC electrode was fabricated and the redox response of Fe3+/2+ couple was analyzed by cyclic voltammetry. The formal potential was observed to change with the FePc fraction, and the most positive value was obtained at the full monolayer coverage. The onset potential of oxygen reduction reaction at the fabricated electrode shifted linearly with the formal potential of FePc. Such a coverage-dependent potential shift was explained in terms of the electronic interaction between FePc and substrate graphene surface based on the X-ray photoelectron spectroscopy as well as the theoretical DFT calculation of a model adsorption system.
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  • Yoshiaki SHIMIZU, Yoshiyuki SUDA, Hirofumi TAKIKAWA, Hitoshi UE, Kazuk ...
    Volume 83 (2015) Issue 5 Pages 381-385
    Released: May 05, 2015
    JOURNALS OPEN ACCESS
    The application of a microporous layer (MPL) between the gas diffusion layer and the catalyst layer (CL) plays a crucial role in the performance of the direct methanol fuel cell (DMFC). To this end, this study investigates the effects of carbon loading and the nature of the carbon material used in the anode MPL on the performance of DMFC using transmission and scanning electron microscopy, polarization technique, and electrochemical impedance spectroscopy (EIS). DMFC was indigenously fabricated using 30 wt% PtRu catalyst supported on carbon nanocoil and commercial Pt catalyst as the anode CL and the cathode CL, respectively. Carbon nanoballoon (CNB) and Vulcan XC-72R (Vulcan) were used as the anode MPL. According to polarization studies, a membrane electrode assembly (MEA) with CNB and Vulcan MPLs (loading of 1.5 mg cm−2) shows higher power density. This is 1.3 and 1.8 times higher than that without the anode MPL when methanol concentration was 0.5 M (M = mol dm−3), respectively. Electrochemical impedance spectra (EIS) results indicate that the MEAs with the anode MPLs have lower high-frequency resistance and charge transfer resistance when compared to those without the anode MPL. Thus, it can be realized that the anode MPL plays a significant role in the effective utilization of CNC-supported PtRu anode catalyst, thereby improving DMFC performance.
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