担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Abstract: The Sn electrode possesses a high selectivity for formate production in electrochemical CO2 reduction. Understanding the relationship between the selectivity of formate and surface characteristics such as structure and chemical state is important for obtaining high activity. In this study, we fabricated a porous Sn electrode using a simple method of anodization in lactic acid. The anodized electrode had numerous 1-μm pores and its surface chemical state had a relatively high ratio of Sn0 compared with that of a bare Sn electrode. In the CO2 reduction reaction, the anodized Sn electrode showed a Faradaic efficiency (FE) of 35% for formate production at a low applied potential of −0.6 V vs. a reversible hydrogen electrode (RHE), with suppressed H2 generation. A Tafel analysis revealed that the slope of the anodized Sn electrode was 70 mV/decade, suggesting an increase in the stability of the CO2 radical anion. These results indicated that a coordinative unsaturation site such as the edge site formed by anodization contributes to a decrease in the overpotential and an increase in the reactive sites for formate production. Moreover, the surface structure appeared to be a significant factor in the production of formate at a very low applied potential relative to the surface oxidation state. Textual abstract: The porous Sn electrode was prepared by anodization in lactic acid to increase the selectivity for formate at a low applied potential. Prepared porous Sn electrode enhances formate production from the CO2RR at a low applied potential due to the stabilization of the CO2 or its reaction intermediates. Graphical Abstract: [Figure not available: see fulltext.].

DOI： 10.1007/s12678-021-00695-2

DOI： 10.1007/s12678-021-00695-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Nitrogen activation, especially dissociation (production of atomic nitrogen), is a key step for efficient nitrogen fixation, such as nitrogen reduction to produce ammonia. Nitrogen reduction reactions using water as a direct hydrogen source have been studied by many researchers as a green ammonia process. We studied the reaction mechanism and found that the nitrogen reduction could be significantly improved via efficient production of atomic nitrogen through electric discharge. In the present study, we focused on packed-bed dielectric barrier discharge (PbDBD) using dielectric beads as the packing material. The experimental results showed that more atomic nitrogen was produced in the nitrogen activation by the discharge in which the discharge space was filled with the dielectric beads than in the nitrogen activation by the discharge without using the dielectric beads. Then, it was clarified that the amount of atomic nitrogen increased as the dielectric constant of the beads to be filled increased, and the amount of atomic nitrogen produced increased up to 13.48 times. Based on the results, we attempted ammonia synthesis using water as a direct hydrogen source with the efficiently generated atomic nitrogen. When the atomic nitrogen gas generated by the PbDBD was sprayed onto the surface of the water phase and subsequently reacted as a plasma/liquid interfacial reaction, the nitrogen fixation rate increased by 7.26-fold compared to that when using the discharge without dielectric beads, and the ammonia production selectivity increased to 83.7%.

DOI： 10.1021/acsomega.1c04201

DOI： 10.1021/acsomega.1c04201

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Persister cells are difficult to eliminate because they are tolerant to antibiotic stress. In the present study, using artificially induced Escherichia coli persister cells, we found that reactive oxygen species (ROS) have greater effects on persister cells than on exponential cells. Thus, we examined which types of ROS could effectively eliminate persister cells and determined the mechanisms underlying the effects of these ROS. Ultraviolet (UV) light irradiation can kill persister cells, and bacterial viability is markedly increased under UV shielding. UV induces the production of ROS, which kill bacteria by moving toward the shielded area. Electron spin resonance-based analysis confirmed that hydroxyl radicals are produced by UV irradiation, although singlet oxygen is not produced. These results clearly revealed that ROS sterilizes persister cells more effectively compared to the sterilization of exponential cells (**p < 0.01). These ROS do not injure the bacterial cell wall but rather invade the cell, followed by cell killing. Additionally, the sterilization effect on persister cells was increased by exposure to oxygen plasma during UV irradiation. However, vapor conditions decreased persister cell sterilization by reducing the levels of hydroxyl radicals. We also verified the effect of ROS against bacteria in biofilms that are more resistant than planktonic cells. Although UV alone could not completely sterilize the biofilm bacteria, UV with ROS achieved complete sterilization. Our results demonstrate that persister cells strongly resist the effects of antibiotics and starvation stress but are less able to withstand exposure to ROS. It was shown that ROS does not affect the cell membrane but penetrates it and acts internally to kill persister cells. In particular, it was clarified that the hydroxy radical is an effective sterilizer to kill persister cells.

DOI： 10.3389/fcimb.2020.00496

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記述言語：英語   掲載種別：研究論文（学術雑誌）

There are multiple active species at the interface between the discharged gas phase and the water phase. Activated nitrogen species are generated in the nitrogen plasma gas by dielectric barrier discharge (DBD). The reaction at the interface between the gas phase containing the activated nitrogen species and water phase (P/L reaction) can produce nitrogen-derived compounds (N-compounds) in water. We have already clarified the mechanism of the P/L reaction focusing on highly active atomic nitrogen in a previous study. In this study, we report the mechanism of the P/L reaction by excited but metastable nitrogen molecules. Involving excited nitrogen molecules [N2(A3ςu+)] with a long lifetime, the reaction selectivity of N-compounds was clarified by quantitative analysis. Moreover, the active species in the water phase (H·, HO·, H2O2) of the P/L reaction were measured, and the involvement of the reaction in the generation of N-compounds was confirmed. The findings clarify that each activated nitrogen species reacts differently with H2O. These results suggest that the occurrence of either an oxidation reaction or a reduction reaction can be regulated by controlling the activated nitrogen species.

DOI： 10.1021/acs.jpcc.0c02392

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記述言語：英語   掲載種別：研究論文（学術雑誌）

In the plasma/liquid (P/L) interfacial reaction, nitrogen fixation is performed on a water phase surface. In the P/L reaction, discharged nitrogen gas reacts with water molecules at the interface between the plasma gas phase and the water phase, followed by either a reduction reaction, ammonia production or oxidation reaction, nitric acid production. The production of nitric acid in the P/L reaction is influenced by the concentration of oxygen present in each gas phase and water phase, and the atomic nitrogen contained in the nitrogen plasma. For the reduction reaction at the P/L reaction locus, the water phase was modulated in order to make ammonia production dominant in nitrogen fixation. Ammonia is released into the gas phase under conditions of high water temperature and high pH. To obtain only ammonia using this reaction, it is necessary to incorporate a process for raising the temperature of the water. In the P/L reaction, only the ammonia gas can be obtained in one-step by using the rise in water temperature due to the discharged heat plasma gas. A reaction system was developed to control the water and the gas phase to enable high purity ammonia trapping as released by the gas phase.

DOI： 10.5796/electrochemistry.19-00080

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.electacta.2020.135805

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

Electric-discharge nitrogen comprises three main types of excited nitrogen species-atomic nitrogen (Natom), excited nitrogen molecules (N2*), and nitrogen ions (N2+) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N-compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The Natom amount was analyzed quantitatively to clarify the contribution of Natom to the P/L reaction. We focused on the quantitative relationship between Natom and the produced N-compounds, and found that both N2* and N2+, which are active species other than Natom, contributed to P/L reaction. The production of N-compounds from N2* and N2+ was enhanced upon UV irradiation of the water phase, but the production of N-compounds from Natom did not increase by UV irradiation. These results revealed that the P/L reactions starting from Natom and those starting from N2* and N2+ follow different mechanisms.

DOI： 10.1002/cphc.201900212

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019 American Chemical Society. The reaction selectivity of an electrode catalyst can be modulated by regulating its crystal structure, and the modified electrode may show different CO 2 reduction selectivity from that of its constituent metal. In this study, we investigated the mechanisms of the electrochemical CO 2 reduction on an electrodeposited Cu 3 Sn alloy by experimental and theoretical analyses. The electrodeposited Cu 3 Sn alloy electrode showed selectivity for CO production at all the applied potentials, and HCOOH production increased with an increase in the applied potential. In particular, hydrocarbon generation was well suppressed on Cu 3 Sn(002). To understand this selectivity change in electrochemical CO 2 reduction, we conducted density functional theory calculations for the reaction on the Cu 3 Sn(002) surface. According to the theoretical analysis, the Cu sites in Cu 3 Sn(002) contributed more to the stabilization of H∗, COOH∗, and CO∗ as compared with the Sn sites. Furthermore, the results indicated that Cu 3 Sn(002) decreased the surface coverage of reaction intermediates such as H∗, COOH∗, and CO∗. We believe that these effects promoted CO∗ desorption while suppressing H 2 generation, CO∗ protonation, and C-C bond formation. The results also suggested that the surface Sn concentration significantly affected the reaction selectivity for HCOOH production from CO 2 .

DOI： 10.1021/acs.jpcc.8b11431

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Among the electrode materials used for electrolytic CO2 reduction, only Cu shows a special function of producing not only carbon monoxide (CO), but also hydrocarbons from CO2. We found that, in electrolytic CO2 reduction using an electrolytically plated Cu-Co electrode, a hydrocarbon product with high faradaic efficiency (FE) could be obtained with low-FE CO. The plated electrodes have a Co solid solution on the Cu surface. The non-localized Co changes the adsorption energy of the reaction intermediate in CO2 reduction. Consequently, by increasing the Co content in Cu, HCOOH can be selectively produced. Further, in electrolytic CO2 reduction with an applied potential of − 1.19 V vs. reversible hydrogen electrode (RHE), the selectivity of methane (CH4) production improved, while the selectivity of ethylene (C2H4) formation lowered. In the reduction using the plated electrode containing 14% Co, the FE of CH4 production reached the highest at 47.7%. These results suggested that mixing Co in Cu promotes the hydrogenation of CH2* to CH3* and inhibits the dimerization of CH2* species. Furthermore, this research on plated electrodes is useful for the development of catalytic electrodes for electrolytic CO2 reduction. [Figure not available: see fulltext.]

DOI： 10.1007/s12678-018-0492-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 Elsevier Ltd In the study, the catalytic edge reactivity on porous Zn electrode has successfully visualized through the electrochemical CO2 reduction to CO. It is well known that the activity of a CO2 reduction reaction catalyst depend on the type of material and surface nano-structure. Consequently, numerous researchers are interested in the relation between the catalyst activity and surface conditions such as morphology, oxidation state, and crystal orientation. However, it is difficult to explain the mechanisms of catalytic CO2 reduction and visualize the catalytic activity. Our results demonstrate, that this strategy not only improved the selective CO production, but also helped visualize the catalytic reactivity on the edge site via open-loop electric potential microscopy (OL-EPM). The obtained OL-EPM image strongly suggests that the edge site of porous Zn acts as an efficient reactive site in the CO2 electrochemical reduction reaction.

DOI： 10.1016/j.electacta.2018.09.080

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 The Royal Society of Chemistry. Ammonia is well known to be a very important chemical substance for human life. Simultaneously, the conventional ammonia production process needs pure nitrogen and pure hydrogen. Hydrogen has been produced from either liquid natural gas (LNG) or coal. In this study, water is used as a direct hydrogen source for ammonia production, thereby obviating the need for catalysts or water electrolysis. We have studied and developed a plasma/liquid interfacial reaction (P/L reaction) that can be used to produce ammonia from air (nitrogen) and water at ambient temperature and pressure, without any catalysts. In this study, the P/L reaction entails enhanced ultraviolet (UV) irradiation of the surface of the water phase. The nitrogen plasma/water interface reaction locus can produce ammonia. In contrast, the vacuum ultraviolet (VUV) irradiated interface reaction locus produces increased amounts of ammonia. In a spin trap electron spin resonance (st-ESR) experiment, large amounts of atomic H (H) were produced by UV irradiation, especially by VUV irradiation. The derived H effectively enhanced the P/L reaction rate.

DOI： 10.1039/c7gc03007j

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© The Electrochemical Society of Japan, All rights reserved. Green cleanup processes for adhered organic fouling on solid surfaces can be successfully performed using a radical vapor reactor (RVR). The RVR can produce large concentrations of reactive oxygen species (ROS, e.g. singlet oxygen (1O2) and hydroxyl radicals (OH)) and can expose them to objective materials. The RVR finds excellent utility in the fields of sterilization and surface functionalization. In this study, RVR is employed in a green cleanup of solid surfaces fouled by an organic polymer and a protein. The RVR produced ROS and removed the adhered organic polymers and proteins from the solid surface. The mechanism of how ROS react with fouling molecules was also elucidated by surface analysis. The greatest advantage of this green RVR cleanup process is that it discharges only air and water. The ROS production and exposure by the RVR successfully cleaned the adhered organic polymer and protein at ambient temperature and pressure without any chemicals. This high-quality, low-cost cleaning technology, which does not require much time and produces no hazardous waste, makes a great contribution to the cleaning industry.

DOI： 10.5796/electrochemistry.18-00036

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.procbio.2017.01.002

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.5796/electrochemistry.84.390

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CiNii Article

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1039/c6gc01560c

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1021/acsnano.5b04049

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Delamination in semiconductor plastic package is a cause of reliability degradation. We have tried to improve the adhesion strength between leadframe and epoxy resin. In this study, organic molecules-metal (Cu) complex "EC tag (Cu)" were employed. It is immobilized on the leadframe surface as adhesion promoter to adhere with thermosetting epoxy resin. In the results, immobilized EC tag (Cu) act as adhesion promoter that shows greater adhesion between leadframe and epoxy resin. Also the leadframe with adhesion promoter doesnt affect semiconductor assembly characteristics.

DOI： 10.1541/ieejsmas.136.31

CiNii Article

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.electacta.2015.08.111

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.5796/electrochemistry.83.721

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CiNii Article

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.colsurfb.2014.10.018

記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1016/j.colsurfb.2013.07.051

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.1128/AEM.01493-13

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記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： 10.3390/s120404952

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開催期間： 2022年07月02日   記述言語：日本語   開催地：北九州国際会議場   国名：日本国  

開催期間： 2022年07月02日   記述言語：日本語   開催地：北九州国際会議場   国名：日本国