著者
Tetsuya YAMADA Satoshi KAWAICHI Akihisa MATSUYAMA Minoru YOSHIDA Nobuhiro MATSUSHITA Ryuhei NAKAMURA
出版者
公益社団法人 電気化学会
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.84, no.5, pp.312-314, 2016-05-05 (Released:2016-05-05)
参考文献数
19
被引用文献数
3

The present study investigated extracellular electron transfer (EET) of Pseudomonas stutzeri, a model organism for bacterial denitrification. Electrochemical cultivation of P. stutzeri in a lithotrophic medium with Fe2+ ions generated the clear cathodic current associated with denitrification reactions. The EET ability of P. stutzeri was greatly strengthened by the addition of acetate, which correlated with the enhanced rate of the enzymatic oxidation of Fe2+. Since the addition of acetate induced the change of cellular metabolisms from lithotrophic denitrification to mixotrophic one, the present finding suggests the effectiveness of EET monitoring as a descriptor of bacterial denitrification activity and changing metabolisms according to the environmental conditions.
著者
Karthik KRISHNAN Tomoaki YAMADA Hiroko IWATSUKI Mitsuo HARA Shusaku NAGANO Kazuya OTSUBO Osami SAKATA Akihiko FUJIWARA Hiroshi KITAGAWA Yuki NAGAO
出版者
公益社団法人 電気化学会
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.82, no.10, pp.865-869, 2014-10-05 (Released:2014-10-05)
参考文献数
36
被引用文献数
1 11

The organized structure and proton transport property in sulfonated polyimide (SPI) thin film have been studied, much less is known at the interfacial charge transport during confinement of such materials. The proton conductivity of SPI thin film is correlated well with the highly oriented polymer structures as determined by infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) and in situ RH dependent synchrotron grazing incidence X-ray diffraction (GI-XRD). The high proton conductivity of 2.8 × 10−1 S cm−1 at 80°C and 90% RH was achieved in the highly oriented SPI thin film. In contrast, the bulk SPI showed the drop of conductivity value at high relative humidity region, which is due to the significant structural disorder accompanied by the strong interaction between the sulfonic acid side chains and water molecules.
著者
Airi YAMAGUCHI Naoki SHIDA Mahito ATOBE Tomoko YAJIMA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.91, no.11, pp.112016, 2023-11-30 (Released:2023-11-30)
参考文献数
35
被引用文献数
1

Photocatalytic single-electron transfer (SET) reactions involving perfluoroalkyl halides play a crucial role in synthetic organic chemistry. However, the electrochemical data for these compounds, which are essential in the discussion of the SET process, are missing. In this study, the electrochemical reduction potentials of perfluoroalkyl halides, alkyl halides, and other analogous compounds were investigated in 0.1 M Bu4NPF6/CH3CN using Ag, Pt, and glassy carbon electrodes. The Ag electrode showed remarkable catalytic properties and a positive reduction peak shift during the reduction reaction; this indicates that the Ag electrode is suitable for estimating the electrochemical potential of the SET process. This study provides a comprehensive dataset for the electrochemical measurements of perfluoroalkyl and alkyl halides, which will help synthetic organic chemists select appropriate reaction systems for these compounds.
著者
Naoya WADA Tomoaki KUMEDA Masashi NAKAMURA Nagahiro HOSHI
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
pp.20-00043, (Released:2020-06-16)
参考文献数
27
被引用文献数
1

Previous study shows that tetra-n-hexylammonium cation (THA+), which is composed of one nitrogen atom and four alkyl chains, increases the activity of the oxygen reduction reaction (ORR) on Pt(111) eight times as high as that of bare Pt(111). We have studied the ORR on Pt single crystal electrodes modified with alkane to elucidate which part of THA+ contributes to the enhancement of the activity for the ORR. The ORR activity is increased only twice by the modification of Pt(111) with dodecane and hexadecane. Combination of a nitrogen atom and alkyl chains of THA+ plays an important role in enhancing the ORR on Pt electrodes. Dodecane and hexadecane increases the ORR activity on Pt(111) and Pt(110), but they deactivate the ORR on Pt(100) and the high index planes.
著者
He SUN Lina SUN Takashi SUGIURA Matthew S. WHITE Philipp STADLER Niyazi S. SARICIFTCI Akito MASUHARA Tsukasa YOSHIDA
出版者
公益社団法人 電気化学会
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.85, no.5, pp.253-261, 2017-05-05 (Released:2017-05-05)
参考文献数
31
被引用文献数
14

Microwave-assisted hydrothermal synthesis of ZnO nanocrystals has resulted in two distinctive structures: hexagonal bi-pyramidal (HBP) and nano-sheet (NS) shapes from Zn(CH3COO)2 solutions containing triethanolamine or benzene tetracarboxylic acid as structure directing agents, respectively. Observation by field-emission scanning electron microscope, high resolution transmission electron microscope as well as analysis of selected area electron beam diffraction patterns revealed that the predominantly exposed facets of HBP and NS ZnO are (102) and (100) faces, occupying 84 and 76% of the total surface area, respectively. Adsorption of D149 and eosin Y photosensitizer dyes onto HBP and NS ZnO was studied in comparison with a randomly structured commercial ZnO nanocrystal (MZ). Density of dye packing was found to be in the order of HBP > MZ > NS, for which HBP was 2 to 5 times higher than NS. Consequently, dye-sensitized solar cells employing HBP ZnO exhibited the highest short circuit photocurrent, but also the lowest open circuit voltage. By contrast, the DSSCs employing NS ZnO exhibited the highest voltage among the three.
著者
竹上 賢吾 古屋 長一
出版者
公益社団法人 電気化学会
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.74, no.10, pp.825-827, 2006-10-05 (Released:2012-03-20)
参考文献数
8
被引用文献数
1 2

Zinc negative electrode has high energy density and less expensive materials for battery in general. However, it generates dendrite when it charged as electrode for secondary battery, therefore, the use for secondary battery is difficult. At this opportunity we would make secondary battery using zinc with aqueous electrolyte. We discovered the dendrite is controlled by glycerin and saccharin in ZnSO4 solution. Lithium manganate is one of opposite electrodes that performed in this condition. In this study, we made aqueous lithium ion-zinc secondary battery with those electrodes and electrolyte, and evaluated then optimized that performance. This battery has approximately 100% charge-discharge efficiency. Their charge and discharge cycle performance depends on concentration of ZnSO4 and mass of LiMn2O4. The density of most suitable ZnSO4 for LiMn2O4 of each mass may be existing. Relatively higher percentage of LiMn2O4 mix has better performance. This battery performed more than 400 charge and discharge cycles as maximum and 70 mAh·g−1 as maximum of discharge capacity was provided. Furthermore, we can expect future improvement of performance as a secondary battery by optimizing these conditions.
著者
Kazuhiro OKAMOTO Yasushi IMADA Naoki SHIDA Yoshikazu KITANO Mahito ATOBE Kazuhiro CHIBA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.91, no.11, pp.112006, 2023-11-28 (Released:2023-11-28)
参考文献数
21
被引用文献数
1

Herein, we report that the 2,7-dimethoxynaphthyl (2,7-DMN) group is a novel electroauxiliary that is readily installed at the N-α position of a carbamate through Friedel–Crafts-type arylation. The resulting N-α C–C bond is easily cleaved through low-potential electrochemical oxidation to give the corresponding iminium cation.
著者
Rumi IZUMIYA Mahito ATOBE Naoki SHIDA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.91, no.11, pp.112003, 2023-11-28 (Released:2023-11-28)
参考文献数
19
被引用文献数
1

β-Scission from alkoxy radical enables selective Csp3-Csp3 bond cleavage under ambient conditions, offering a useful method for organic synthesis. Various photocatalytic systems for β-scission have been reported, where proton-coupled electron transfer (PCET) mechanism plays a key role in the generation of alkoxy radical and thus β-scission. Electrochemical β-scission has been mainly pioneered in the presence of mediator, and a direct electrochemical system has rarely been investigated. Here, we investigated the β-scission via direct electrochemical oxidation using a model compound with β-O-4 linkage. Synthetic experiments suggested smooth progress of β-scission in the presence of collidine as a base. Cyclic voltammetry measurement, voltammetric simulation, and quantum simulation suggested the PCET mechanism is responsible for the electrochemical reaction, which is followed by β-scission process. This report provides fundamental insights into the electrochemical β-scission via direct electron transfer on the electrode, which contribute to future applications such as biomass valorization.
著者
Shohei YOSHINAGA Mahito ATOBE Naoki SHIDA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.91, no.11, pp.112002, 2023-11-28 (Released:2023-11-28)
参考文献数
14

Redox behavior is a fundamental and fascinating feature of polycyclic aromatic hydrocarbons (PAHs). Cyclic voltammetry (CV) measurements are commonly performed to estimate the electronic structure of PAHs and to determine the stability of their oxidation and reduction states. However, the influences of electrolytes on electrochemically oxidized/reduced PAHs have rarely been discussed. In this note, we report voltammetric analyses of five PAHs (anthracene, 9,10-dimethylanthracene, phenanthrene, pyrene, and perylene) in Bu4NB(C6F5)4/CH2Cl2 and Bu4NTfO/CH2Cl2, respectively, to highlight how the electrolyte-coordination affects the oxidative voltammetric behavior of PAHs. In most cases, reversible voltammetric responses were obtained with Bu4NB(C6F5)4/CH2Cl2, suggesting that this electrolyte is enough weakly coordinating to investigate its intrinsic oxidation behavior. On the other hand, irreversible voltammetric responses were obtained with Bu4NTfO/CH2Cl2, indicating that the presence of a relatively coordinating anion, TfO−, destabilizes the radical cation species and induces further chemical and electrochemical processes. This study provides hints for rational electrolyte design to properly understand the redox behavior of molecules and maximize the potential of functional molecules for applications related to redox chemistry.
著者
Yasuyuki OKUMURA Eisuke SATO Koichi MITSUDO Seiji SUGA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.91, no.11, pp.112007, 2023-11-28 (Released:2023-11-28)
参考文献数
34

The electrochemical synthesis of dibenzothiophene S,S-dioxides was achieved by the anodic oxidation of biaryl sulfonyl hydrazides. The use of Bu4NOTf as the electrolyte in HFIP/CH3NO2 (15 : 1) is essential. Several biaryl sulfonyl hydrazides followed by dibenzothiophene S,S-dioxides under mild electrochemical conditions. Control experiments and density functional theory calculations suggested that the electrooxidation of biaryl sulfonyl hydrazides would generate sulfonyl radicals or sulfonyl cations which were converted to dibenzothiophene S,S-dioxides.
著者
Eisuke SATO Sayaka OGITA Koichi MITSUDO Seiji SUGA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.91, no.11, pp.112005, 2023-11-28 (Released:2023-11-28)
参考文献数
26

Cathodic reduction efficiently cleaved N–O bonds. The simple cathodic reduction of Weinreb amides in a divided cell afforded the corresponding amide in good yields. Cyclic voltammetry experiments and density functional theory calculations suggested that the direct reduction of the N-methoxy amide generates the methoxy radical and amide anion. The release of methanol derived from methoxy radical would be the driving force of the N–O bond cleavage.
著者
Yoshimasa SUZUKI Minoru MIZUHATA
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
vol.90, no.10, pp.103001, 2022-07-11 (Released:2022-07-11)
参考文献数
40
被引用文献数
1 3

We have established a method for measuring the zeta potential generated at the interface between a nonaqueous electrolyte solution utilized in LiClO4/propylene carbonate (PC) electrolyte and lithium cobalt oxide (LiCoO2) by the streaming potential method. Since the surface potential of the metal oxide dispersed in the aprotic nonaqueous solvent contains only a very small amount of water-based potential-determining ions such as H+ and OH−, the potential is determined by the adsorption of the solvated electrolyte itself. Unlike aqueous systems with potential-determining ions that exhibit specific adsorption, it took a very long time until the equilibrium state of the ion distribution near the solid surface was reached and the potential stabilized, with a time constant that amounted to about 5 minutes. Therefore, a detailed analysis of the change over time of the potential after the pressure setting showed that the predictive potential showed a change over time with almost a single relaxation having certain time constant. The measurement time of the streaming potential was corresponded to about the time constant, and the resulting zeta potential showed an anomalous concentration dependence as a maximum around 1.0 mol L−1 PC and a minimum at 1.5 mol L−1 PC for the concentration of each solution.
著者
Athchaya SUWANSOONTORN Katsuhiro YAMAMOTO Shusaku NAGANO Jun MATSUI Yuki NAGAO
出版者
The Electrochemical Society of Japan
雑誌
Electrochemistry (ISSN:13443542)
巻号頁・発行日
pp.21-00042, (Released:2021-05-21)
参考文献数
47
被引用文献数
2

Investigation of interfacial proton transport is necessary to elucidate biological systems. As commonly found in biomaterials, the carboxylic acid group was proven to act as a proton-conducting group. This study investigated the influence of carboxylic acid concentration on both interfacial and internal proton transport. Several styrene-based polymers containing the carboxylic acid group were synthesized. The amount of carboxylic acid group in the polymer chain was varied to explore the effects of weak acid concentration on polymer thin films’ electrical properties. The IR p-polarized multiple-angle incidence resolution spectrometry (pMAIR) spectra show the higher ratio of the free carboxylic acid groups rather than cyclic dimers in polymers with a higher concentration of carboxylic acid group, facilitating the more hydrogen bonding networks in films. The water uptake results reveal the similar number of adsorbed water molecules per carboxylic acid group in all thin films. Remarkably, polymer thin films with high carboxylic acid concentration provide internal proton conduction because of the relative increase in the amount of the free carboxylic acid group. In contrast, interfacial proton conduction was found in low carboxylic acid concentration polymers because of the relatively large amount of cyclic dimer carboxylic acid group and poor amount of free carboxylic acid group. This study provides insight into interfacial proton transport behavior according to the weak acid concentration, which might explain proton transport in biological systems.