研究者詳細 - 萩尾　健史

論文 - 萩尾　健史

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Utilization of agricultural waste to herbicide removal: Magnetic BEA zeolite adsorbents prepared by dry-gel conversion using rice husk ash-derived SiO2 for paraquat removal 査読有り国際共著国際誌

Phouthavong Vanpaseuth, Hagio Takeshi, Park Jae-Hyeok, Nijpanich Supinya, Srihirunthanon Teeranun, Chantanurak Nutchanan, Duangkhai Kanchanok, Rujiravanit Ratana, Chounlamany Vanseng, Phomkeona Kesiny, Kong Long, Li Liang, Ichino Ryoichi

ARABIAN JOURNAL OF CHEMISTRY 16 巻 ( 8 ) 2023年8月

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）出版者・発行元：Arabian Journal of Chemistry

This study presents a method that will allow for the sustainable utilization of rice husk ash-SiO2 (RHAS), an agricultural-waste–derived material, as a bulky solid SiO2 source in the zeolite beta (BEA)/Fe3O4 composite (magnetic RHAS-BEA) synthesis via a dry-gel conversion method for the removal of paraquat, a typical herbicide, from aqueous solutions. Ultrasonic waves were used to facilitate the formation of uniform Fe3O4-contained dry precursor gel before converting to the magnetic BEA zeolite composite for the first time. Magnetic RHAS-BEA was then characterized and compared with a non-magnetic sample (RHAS-BEA) using X-ray diffraction and field-emission scanning electron microscopy. In terms of adsorption, we found that paraquat had a high adsorption rate on the samples and conformed to a pseudo-second-order kinetic model. The adsorption behavior of paraquat on the synthesized RHAS-BEA and magnetic RHAS-BEA obeyed the Langmuir adsorption isotherm model. The synthesized adsorbents were reusable for at least four cycles, via thermal regeneration at 450 °C. The inclusion of Fe3O4 particles in magnetic RHAS-BEA disrupted neither the crystallization of the BEA zeolite nor the adsorption of paraquat and enabled easy collection via an external magnet.

DOI： 10.1016/j.arabjc.2023.104959

Dry-gel conversion synthesis of magnetic BEA-type zeolites for antibiotics adsorption 査読有り国際共著国際誌

Phouthavong Vanpaseuth, Hagio Takeshi, Nijpanich Supinya, Park Jae-Hyeok, Hiraiwa Masatake, Srihirunthanon Teeranun, Chantanurak Nutchanan, Rujiravanit Ratana, Kamimoto Yuki, Li Xinling, Kong Long, Li Liang, Ichino Ryoichi

JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY 105 巻 ( 2 ) 頁： 511 - 524 2023年2月

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）出版者・発行元：Journal of Sol-Gel Science and Technology

The dry-gel conversion method (DGC) is a promising synthesis protocol for preparing magnetic zeolite composites as it yields homogeneous composite particles with more rapid crystallization, smaller reactor volume, and less waste production than the conventional hydrothermal method. This work investigates the optimal conditions for preparing magnetic BEA-type zeolites using the DGC method, including the gel/water ratio, crystallization temperature and time. Precursor dry-gel incorporating well-dispersed magnetite was subjected to crystallization under water vapor atmosphere with a gel/water ratio of 0.5–2, crystallization temperature of 140–200 °C for 1.5–12 h, followed by characterization using X-ray diffraction and scanning electron microscopy. The optimum conditions were found to be gel/water ratio of 1 and crystallization at 180 °C for 12 h. Magnetic properties of collected samples were evaluated using a vibrating-sample magnetometer after calcination at 400–500 °C for 12 h. Products calcined below 450 °C showed good magnetic properties. Adsorption of sulfadiazine using the BEA and magnetic BEA-type zeolites was evaluated in a 10–50 mg/l range. Results revealed favorable multilayer-type adsorption of sulfadiazine onto both non-magnetic and magnetic BEA-type zeolites (Freundlich model). These indicate that DGC method is suitable for preparing high-silica magnetic BEA-type zeolites with potential for antibiotic removal. Graphical Abstract: [Figure not available: see fulltext.].

DOI： 10.1007/s10971-022-06025-2

Electrodeposition of Amorphous Molybdenum Oxide on Iron-Group Element Based Plating and its Novel Application as a Corrosion Protective Coating 査読有り国際共著国際誌

Park Jae-Hyeok, Hagio Takeshi, Nijpanich Supinya, Chanlek Narong, Chaiprapa Jitrin, Songsiriritthigul Chomphunuch, Songsiriritthigul Prayoon, Ichino Ryoichi

JOURNAL OF THE ELECTROCHEMICAL SOCIETY 169 巻 ( 7 ) 2022年7月

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）出版者・発行元：Journal of the Electrochemical Society

The corrosion resistance of materials composed of metal is an essential property for preventing material deterioration caused by corrosion. In this study, we demonstrate that corrosion resistance can be significantly improved through the electrodeposition of molybdenum oxide onto a metal plating containing iron-group elements. Mo oxide can be electrodeposited using a simple plating bath, low current density, and short deposition time, exhibiting a fascinating metallic gloss appearance. GI-XRD and XPS analyses revealed that amorphous Mo oxide adhered to the substrate by a seed layer partially reduced to metallic Mo by the iron-group element in the substrate, based on the principle of "induced co-deposition."A Mo oxide coating with a thickness of approximately 100 nm decreases the corrosion current density of Ni-W plating by approximately 5 times and the passivation current density by approximately 10 times in a 3 mass% NaCl solution. Mo oxide coatings represent an attractive strategy for improving the corrosion resistance of various metal materials containing iron-group elements.

DOI： 10.1149/1945-7111/ac7e78

A tri-layer floating photocatalyst/adsorbent for the removal of organic compounds from wastewater: Layer-by-layer deposition of silicalite-1 and titania on hollow glass microspheres 査読有り国際共著国際誌

Environmental Technology and Innovation 26 巻 2022年5月

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）出版者・発行元：Environmental Technology and Innovation

Removal of organic compounds from wastewater is necessary to ensure that aquatic organisms are not adversely affected. In the past, it had been shown that zeolite-based systems provide good opportunities for wastewater treatment; however, most of the zeolite systems reported thus far face the disadvantages of sinking in water and saturated adsorption site. Therefore, in the current study, we attempted to develop zeolite-based composite systems with good floatability, adsorption capacity, and photocatalytic activity. In addition, our aim was to ensure that these composites could be easily separated from the treated water. Thus, a tri-layer floating photocatalyst/adsorbent was prepared via the layer-by-layer deposition of silicalite-1, a pure silica MFI-type zeolite (PSZ), and TiO2 on hollow glass microspheres (HGMs). A thin layer of silicalite-1 was crystallized on the dense walls of HGMs to fabricate floating adsorbents (PSZ-HGMs). Subsequently, a layer of TiO2 was deposited on PSZ-HGM surfaces using the sol–gel method to develop photocatalytic composites (TiO2/PSZ-HGMs). A good PSZ coverage and attachment were achieved on HGM surfaces by adding HGMs to an alkali solution containing tetrapropylammonium hydroxide and tetraethyl orthosilicate, followed by hydrothermal synthesis at 180 °C for 40 h. Subsequent deposition of TiO2 was effective in homogeneously covering the PSZ surface without clogging the zeolite pores. The wastewater treatment capacity of the synthesized materials was verified using methylene blue (MB). It was found that TiO2/PSZ-HGMs, which exhibited both photocatalytic and adsorption activities, acted synergistically with UV-C irradiation to drastically degrade MB concentration by ∼98% within 2 h. Therefore, these materials may be considered to have high potential in wastewater-treatment processes.

DOI： 10.1016/j.eti.2021.102242

Development of novel nanoporous hexagonal tungsten oxide membrane for separation of water/acetic acid mixtures via pervaporation 査読有り国際誌

Kunishi Hiroto, Hagio Takeshi, Wada Shintaro, Kamimoto Yuki, Ichino Ryoichi

JOURNAL OF MEMBRANE SCIENCE 620 巻 2021年2月

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）出版者・発行元：Journal of Membrane Science

A novel nanoporous hexagonal tungsten oxide (NP-h-WO3) membrane was developed for separating water/acetic acid (H2O/AcOH) mixtures. The nanopores on the c-plane of h-WO3 are larger than H2O molecules and smaller than AcOH molecules and thus should allow for their effective separation. Moreover, h-WO3 exhibits high stability in acids (pH < 4). Therefore, c-axis-aligned NP-h-WO3 membranes are promising for the separation of H2O/AcOH mixtures. Given this background, we report, for the first time, the synthesis of c-plane-aligned dense NP-h-WO3 membranes on porous ceramic supports via the hydrothermal method using a precursor solution containing AcOH. The presence of AcOH and the concentration of Na2WO4 in the precursor solution are the key factors affecting crystal growth and alignment along the c-plane. A high Na2WO4 concentration is necessary for obtaining membranes with a high degree of c-plane alignment. Thus, dense, c-plane-aligned NP-h-WO3 membranes could be fabricated by precoating the support with amorphous WO3 seeds and subsequent hydrothermal synthesis in a precursor solution of Na2O/WO3/AcOH/H2O (1/1/0.88/201) at 180 °C for 24 h. The fabricated membranes exhibited a maximum separation factor of 42.6 during the pervaporation of a H2O/AcOH mixture (10/90 (w/w)) at 80 °C. Thus, these NP-h-WO3 membranes are highly suited for H2O/AcOH separation.

DOI： 10.1016/j.memsci.2020.118860

Electrodeposition of nano-diamond/copper composite platings: Improved interfacial adhesion between diamond and copper via formation of silicon carbide on diamond surface 査読有り国際誌

Hagio Takeshi, Park Jae-Hyeok, Naruse Yuto, Goto Yasuki, Kamimoto Yuki, Ichino Ryoichi, Bessho Takeshi

Surface and Coatings Technology 403 巻 2020年12月

Removal of heavy metals by BEA zeolite/Fe<inf>3</inf>O<inf>4</inf> composite prepared via dry-gel conversion method using agrowaste-derived raw material 査読有り国際共著国際誌

Phouthavong V., Hagio T., Park J.H., Nijpanich S., Duangkhai K., Rujiravanit R., Thaveemas P., Chounlamany V., Kong L., Li L., Ichino R.

Solid State Sciences 149 巻 2024年3月

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）出版者・発行元：Solid State Sciences

Using agrochemicals are considered as an anthropogenic source of heavy metal contamination in water, and ecofriendly remediation tools for removal is desired. Here, we demonstrate material circulation by converting SiO2 extracted from agrowaste: rice husk ash, into an easily collectable adsorbent: BEA zeolite/Fe3O4 composite, through dry-gel conversion technique. In addition, the synthesized BEA zeolite/Fe3O4 composite was tested for removal of heavy metals for the first time. Instrumental analyses confirmed that incorporated Fe3O4 particles inside BEA zeolites showed no severe effects on its morphologies. Pseudo-second order kinetic and Langmuir isotherm models were found best described the adsorption of three typical toxic heavy metals: Pb(II), Cu(II), Zn(II). Moderate adsorption capacities of 0.675, 0.310, and 0.308 mmol/g for Pb(II), Cu(II), and Zn(II), respectively, following the selectivity order: Pb(II) > Cu(II) ≈ Zn(II) were obtained. The composite adsorbent exhibits magnetic collectability, reusability and stability, indicating its practicality for removal of heavy metals from water.

DOI： 10.1016/j.solidstatesciences.2024.107473

Super hardening of Fe–W alloy plating by phase transformation of amorphous to metal carbides-dispersed nanocrystalline alloys and application as promising alternative for hard chromium plating 査読有り国際共著国際誌

Park J.H., Kim J.I., Shinohara Y., Hagio T., Umehara N., Ichino R.

Surface and Coatings Technology 477 巻 2024年2月

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）出版者・発行元：Surface and Coatings Technology

Despite the superior hardness, wear resistance, and corrosion resistance of hard chromium (Cr) plating using toxic hexavalent chromium (Cr6+), the gradual restriction on the use of Cr6+ in industrial fields necessitates the development of an alternative, harmless plating material with excellent performance. Here, we report the fabrication of super-hard plating by the simple annealing of electrodeposited Fe–W–C plating as a promising alternative for hard Cr plating. Amorphous-structured Fe–W–C plating, including co-deposited citric acid-derived carbon, forms uniformly dispersed ternary metal carbides inside the plating during annealing, which changes the plating structure from amorphous to nano-carbide-dispersed alloys. The phase-transformed, nanocrystalline Fe–W–C alloy annealed at 700 °C exhibited a maximum hardness of 20.5 GPa, which surpassed the hardness of hard Cr plating (12.5 GPa). The ball-on-disc tribo-test and corrosion test results further demonstrated the superior wear and anti-corrosion properties of the carbide-dispersed Fe–W–C alloy plating compared with hard Cr plating. This study develops the applicability of this super-hard plating as a new hard coating material that overcomes the limitations of conventional metal plating without using any toxic chemical.

DOI： 10.1016/j.surfcoat.2024.130388

Nanoarchitectonics Solution Plasma Polymerization of Amino-Rich Carbon Nanosorbents for Use in Enhanced Fluoride Removal 査読有り国際誌

Tipplook, M; Tanaka, H; Sudare, T; Hagio, T; Saito, N; Teshima, K

ACS APPLIED MATERIALS & INTERFACES 16 巻 ( 6 ) 頁： 7038 - 7046 2024年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACS Applied Materials and Interfaces

Amino-functionalized carbon (NH2C) is an effective adsorbent in removing pollutants from contaminated water because of its high specific surface area and electrical charge. In the conventional preparation method, the introduction of amino groups onto the carbon surface is limited, resulting in low pollutant adsorption. Herein, we present simultaneous carbonization and amination to form NH2C via electrical discharge of nonequilibrium plasma, and the resultant material is applied as an effective adsorbent in fluoride removal. The simultaneous process introduces numerous amino groups into the carbon framework, enhancing the adsorption efficiency. The fluoride adsorption capacity is approximately 121.12 mg g-1, which is several times higher than those reported in previous studies. Furthermore, computational modeling is performed to yield deeper mechanistic insights into the molecular-level adsorption behavior. These data are useful in designing and synthesizing advanced materials for applications in water remediation.

DOI： 10.1021/acsami.3c15172

c面配向六方晶酸化タングステン膜の分子ふるい型分離膜としての可能性招待有り査読有り国際共著

萩尾健史, 國司寛人, 和田慎太郎, 寺尾年弘, 木下空, プッタヴーンワンパサート, ニッチパーニッチスーピンヤー, パクジェヒョク, 市野良一

ゼオライト 41 巻 ( 1 ) 頁： 9 - 19 2024年1月

担当区分：筆頭著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本ゼオライト学会

カーボンニュートラルおよび持続可能な社会の実現に向け，エネルギー消費の大きい分離プロセスの省エネルギー化や資源循環に貢献する分離膜は益々注目されている。その中で，膜材料の検討は分離特性を決定づける重要な研究要素の一つである。分子サイズのミクロ細孔を有する無機結晶（ミクロ多孔無機結晶）は分子ふるいとも呼ばれる有望な分離膜材料である。筆者らは，この分子ふるい型膜材料として新たに六方晶酸化タングステンの可能性を提案してきた。同材料は，結晶のc軸と並行な一軸細孔を有するため，そのc面配向膜は分子ふるい型分離膜として機能すると予想されるが，分離膜材料としては検討されてこなかった。本稿では，筆者らが種々の対策によって緻密なc面配向六方晶酸化タングステン膜の合成に挑戦し，液分離並びにガス分離への適用可否を検討した結果を紹介する。得られた膜は，水／酢酸の混合溶液から水を選択的に分離できることが確認された。また，各種液およびガス分子の透過特性を調査した結果，ミクロ細孔を利用した小分子向けの分子ふるい型分離膜として機能するであろうことを見出した。本発見は膜材料の選択肢拡大に寄与すると期待される。

DOI： 10.20731/zeoraito.41.1.9

Effects of the Topological Structure of Different Cu-Zeolites on the Relationship between Soot and NO<sub>x</sub> Removal on NH<sub>3</sub>-SCRF 査読有り国際共著国際誌

Ye, ZM; Zhao, PC; Tang, XC; Hagio, T; Sato, K; Nagaoka, K; Li, XL

ENERGY & FUELS 38 巻 ( 3 ) 頁： 2212 - 2223 2024年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Energy and Fuels

Experimental studies were carried out to explore the effect of zeolite topology on NOx purification and soot oxidation in ammonia selective catalytic reduction coated diesel particulate filter (SCRF) catalysts. The catalytic activity of Cu-exchanged zeolites Cu/SSZ-13 (CHA topology), Cu/ZSM-5 (MFI), and Cu/BEA(BEA) was evaluated in the NH3-SCRF. Experiments with XRD and ICP-SFMS demonstrated that the three types of samples retained their typical structural peaks after Cu modification, and the similar ratios of Cu/Al and Si/Al ensure that the primary cause of different catalytic performances was caused by different framework structures. As determined by laboratory experiments with synthetic gas, Cu/SSZ-13 exhibited an extended activity window and a higher deNOx efficiency at NO2/NOx below 0.5. In addition, Cu/ZSM-5 consistently exhibited superior CO2 selectivity in soot-loading experiments, regardless of the NO2 concentration. When loaded with soot, Cu/BEA exhibited exceptional deNOx performance at NO2/NOx = 0.5. NH3 was observed to have a negative effect on soot oxidation by NO2, while the consumption of NO2 by soot oxidation contributed to the NO2-SCR reaction being aided. Influenced by different zeolite structural features, the degree of diffusion of copper in the zeolite as well as the replacement sites are different, thus forming different ratios of copper species. For instance, the presence of Z2Cu sites, which can adsorb more NH3 molecules than ZCuOH sites as indicated by the in situ DRIFTS results, and the presence of Cu+ with stronger redox properties compared to Cu2+, can be influenced by these structural characteristics. Additionally, soot particles have the ability to act as adsorption sites for the NH3-SCR reaction.

DOI： 10.1021/acs.energyfuels.3c03034

AC Electromagnetic Field Controls the Biofilms on the Glass Surface by Escherichia coli & Staphylococcus epidermidis Inhibition Effect 査読有り国際共著国際誌

Aoyama, N; Kanematsu, H; Barry, DM; Miura, H; Ogawa, A; Kogo, T; Kawai, R; Hagio, T; Hirai, N; Kato, T; Yoshitake, M; Ichino, R

MATERIALS 16 巻 ( 21 ) 2023年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials

Biofilms, mainly comprised of bacteria, form on materials’ surfaces due to bacterial activity. They are generally composed of water, extracellular polymeric substances (polysaccharides, proteins, nucleic acids, and lipids), and bacteria. Some bacteria that form biofilms cause periodontal disease, corrosion of the metal materials that make up drains, and slippage. Inside of a biofilm is an environment conducive to the growth and propagation of bacteria. Problems with biofilms include the inability of disinfectants and antibiotics to act on them. Therefore, we have investigated the potential application of alternating electromagnetic fields for biofilm control. We obtained exciting results using various materials’ specimens and frequency conditions. Through these studies, we gradually understood that the combination of the type of bacteria, the kind of material, and the application of an electromagnetic field with various low frequencies (4 kHz–12 kHz) changes the circumstances of the onset of the biofilm suppression effect. In this study, relatively high frequencies (20 and 30 kHz) were applied to biofilms caused by Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis), and quantitative evaluation was performed using staining methods. The sample surfaces were analyzed by Raman spectroscopy using a Laser Raman spectrometer to confirm the presence of biofilms on the surface.

DOI： 10.3390/ma16217051

Synthesis of Sulfur-Doped Magnetic Iron Oxides for Efficient Removal of Lead from Aqueous Solutions 査読有り国際共著国際誌

Xu, JQ; Pan, MT; Zou, C; Huang, XQ; Hagio, T; Ichino, R; Kong, L; Li, L

WATER 15 巻 ( 20 ) 2023年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Water (Switzerland)

Heavy metal pollution poses an environmental risk, and its efficient removal and facile separation from water remains a challenge. Magnetic iron oxide, an eco-friendly, relatively stable, and easy-separation material, has been regarded as one of the most applicable adsorbents for water treatment. However, the limited adsorption capacity has restricted its applications. Herein, sulfur-doped magnetic Fe3O4 (Sx–Fe3O4) adsorbent was fabricated using a calcination method for the efficient removal of Pb(II) from water. In contrast to undoped Fe3O4, the introduction of doped sulfur greatly enhanced the adsorption performance of S–Fe3O4 over four times, with a maximum capacity of 333.33 mg g−1, which was synthesized at 300 °C with a raw molar ratio of S–Fe of 5. Based on the structure and morphology analysis, it was demonstrated that sulfur was successfully doped into the Fe3O4 structures, which resulted in Fe3O4 with active sulfur sites accordingly contributing to the adsorption enhancement through the combination of strong soft–soft interactions between soft base sulfur and soft acid Pb(II) along with surface adsorption. Sx–Fe3O4 could maintain the adsorption performance in the presence of competing ions. Furthermore, although the sulfur doping process exhibited slight side effects on the magnetic property, magnetic Sx–Fe3O4 maintained the high separation potential. This study presented a promising strategy to enhance the adsorption performance of Fe3O4 through sulfur doping for Pb(II) removal from water.

DOI： 10.3390/w15203667

Preparation and Characterization of TiO(2)-Coated Hollow Glass Beads for Functionalization of Deproteinized Natural Rubber Latex via UVA-Activated Photocatalytic Degradation. 査読有り国際共著国際誌

Nijpanich S, Nimpaiboon A, Rojruthai P, Park JH, Hagio T, Ichino R, Sakdapipanich J

Polymers 15 巻 ( 19 ) 2023年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymers

The photochemical degradation of natural rubber (NR) is a prevalent method used to modify its inherent properties. Natural rubber, predominantly derived from the Hevea Brasiliensis tree, exhibits an exceptionally high molecular weight (MW), often reaching a million daltons (Da). This high MW restricts its solubility in various solvents and its reactivity with polar compounds, thereby constraining its versatile applications. In our previous work, we employed TiO2 in its powdered form as a photocatalyst for the functionalization of NR latex. However, the post-process separation and reuse of this powder present substantial challenges. In this present study, we aimed to functionalize deproteinized NR (DPNR) latex. We systematically reduced its MW via photochemical degradation under UVA irradiation facilitated by H2O2. To enhance the efficiency of the degradation process, we introduced TiO2-coated hollow glass beads (TiO2-HGBs) as photocatalysts. This approach offers the advantage of easy collection and repeated reuse. The modified DPNR showed a reduction in its number-average MW from 9.48 × 105 to 0.28 × 105 Da and incorporated functional groups, including hydroxyl, carbonyl, and epoxide. Remarkably, the TiO2-HGBs maintained their performance over seven cycles of reuse. Due to their superior efficacy, TiO2-HGBs stand out as promising photocatalysts for the advanced functionalization of NR across various practical applications.

DOI： 10.3390/polym15193885

Room-Temperature Bulk Supramolecular Polymer Based on C<inf>3</inf>-Symmetrical Benzene-1,3,5-tricarboxamides Having Two-Armed Alkyl Groups as Side Chains 査読有り国際誌

Ishigaki Y., Yamanaka M., Hagio T., Ichino R.

ChemistrySelect 8 巻 ( 35 ) 2023年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ChemistrySelect

To develop a bulk supramolecular polymer based on 1,3,5-benzenetricarboxamide (BTA) without crystallinity at room temperature, C3-synmetrical BTA derivatives with two-armed alkyl groups were synthesized and characterized. IR and XRD measurements of the BTA derivatives suggested that the higher-order structure obtained using these materials was hexagonal columnar, owing to the characteristic three-fold hydrogen bonding. In DSC measurements, BTA having 10-nonadecyl groups (10NDBTA) showed only a single transition point at 233 °C and maintained its mesophase down to −50 °C, whereas the other BTA derivatives showed a transition peak in the range of 20 to 131 °C and another in the range of 204 to 239 °C, corresponding to alkyl melting and dissociation of the stacked BTA cores, respectively. 13C-SSNMR measurement of 10NDBTA indicated that not only the 10-nonadecyl groups of the side chains but also the BTA cores forming the main chain of the supramolecular polymer show a unique high mobility even at ambient temperature.

DOI： 10.1002/slct.202300805

Gas permeation properties of c-plane aligned hexagonal tungsten oxide membranes formed by multi-stage synthesis 査読有り国際共著国際誌

Wada Shintaro, Hagio Takeshi, Kunishi Hiroto, Park Jae-Hyeok, Phouthavong Vanpaseuth, Yamada Yuta, Terao Toshihiro, Li Xinling, Nijpanich Supinya, Ichino Ryoichi

JOURNAL OF THE KOREAN CERAMIC SOCIETY 2023年8月

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）出版者・発行元：Journal of the Korean Ceramic Society

Crystalline microporous membranes are promising tools for gas separation because their molecular dimension pores allow us to accurately sieve molecules by size. Recently, microporous hexagonal WO3 was reported as a new potential membrane material and its membrane was found to enable separation of water from water/acetic acid mixtures. Pore size of hexagonal WO3 seemed to be also suitable for separation of small gasses; however, its gas permeation properties have not been reported. Additionally, densification of membranes by decreasing intercrystalline gaps are extremely important in gas separation. One effective method to densify polycrystalline membranes is to repeat membrane synthesis, namely multi-stage synthesis. Here, we attempt to prepare dense hexagonal WO3 membranes on porous tubular supports by multi-stage synthesis and examined their densification and gas permeation properties. Densification was confirmed by permeation of SF6 (gas molecule larger than pores of hexagonal WO3), and its potential for separating small gasses was considered from single gas permeation of He and He/SF6 permselectivity. The results indicated that the multi-stage synthesis is effective to densify the membranes and He/SF6 permselectivity reached 42.8 for three-stage synthesis under modified conditions, implying hexagonal WO3 is a potential membrane material for small gas separation.

DOI： 10.1007/s43207-023-00321-5

An effective strategy for improving the performance of electrodeposited Fe-W alloy plating: Tailoring microstructure by graphene incorporation 査読有り国際共著国際誌

Shinohara Yu, Park Jae-Hyeok, Hagio Takeshi, Kim Jae-Il, Lee Woo-Young, Umehara Noritsugu, Ichino Ryoichi

MATERIALS & DESIGN 230 巻 2023年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials and Design

Despite the excellent performance of hard Cr plating using hexavalent chromium (Cr6+), its use is being restricted owing to recent environmental regulations. Electrodeposited Fe-W alloy is considered a possible alternative, but its high coefficient of friction (COF), high wear rate owing to tribo-oxidation, and high corrosion rate hinder its practical application. In this study, we attempted to solve these problems by modifying the microstructure of Fe-W alloy by incorporating 2D-structured graphene. The effect of graphene incorporation on the structure of the Fe-W alloy and its properties, especially microhardness, wear, and corrosion resistance, were investigated. The results showed the graphene effectively modified the columnar structure of the Fe-W alloy by inhibiting the vertical growth of clusters during electrodeposition, leading to fragmentation of the vertical cluster boundaries. This improved the hardness by as much as 17 % up to 9.1 GPa, and the corrosion resistance by changing the corrosion mechanism from localized corrosion to uniform corrosion. In addition, the graphene reduced the COF and wear rate by reducing the Fe2O3 formed by tribo-oxidation to a lower oxidation state. The structural modification of the plating by graphene incorporation thus provides an effective solution to improving the performance of Fe-W alloys.

DOI： 10.1016/j.matdes.2023.111938

Improvement in the corrosion resistance of electrodeposited Ni-W alloy by MWCNT co-deposition and prevention of metal-carbon interfacial corrosion by carbide formation 査読有り国際誌

Park Jae-Hyeok, Hagio Takeshi, Ichino Ryoichi

JOURNAL OF ALLOYS AND COMPOUNDS 939 巻 2023年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Alloys and Compounds

Composite plating is an effective method which can enhance the properties of conventional metal plating by co-deposition of composite materials. In this study, multi-walled carbon nanotubes (MWCNTs) were used as a composite material to improve the corrosion resistance of Ni-W alloys, and the effect of the MWCNTs addition on the anti-corrosion properties was discussed. The corrosion current density of the Ni-W/MWCNTs composite decreased approximately 4 times from 16.6 to 4.6 μA·cm-2 in 3 wt% NaCl solution compared to the pristine Ni-W; this showed that the co-deposition of MWCNTs was effective for improvement in the corrosion resistance. However, the interfacial corrosion between the metal matrix and MWCNTs occurred in the high potential region and degraded the passivation properties of plating. This interfacial corrosion is caused by the high O content due to the hydroxyl groups on the acid-treated MWCNTs surface and the difference in W concentration between the interface of MWCNTs and the Ni-W matrix. Heat treatment in Ar atmosphere removes these hydroxyl groups and diffuses Ni and W into MWCNTs to form metal carbide (Ni6W6C), effectively alleviating interfacial corrosion. This study presents interfacial corrosion can be effectively mitigated by forming metal carbides at the interface of carbon materials in metal/carbon composites.

DOI： 10.1016/j.jallcom.2023.168788

Preliminary Study on Electrodeposition of Copper Platings and Codeposition of Carbon Nanotubes from Organic Solvent 査読有り国際共著国際誌

Park Jae-Hyeok, Fujita Yusei, Hagio Takeshi, Phouthavong Vanpaseuth, Kamimoto Yuki, Bessho Takeshi, Ichino Ryoichi

COATINGS 13 巻 ( 4 ) 2023年4月

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）出版者・発行元：Coatings

Metal/carbon composite plating is an effective strategy for improving and adding properties to metal plating by incorporating carbon materials into the metal matrices. Copper (Cu) is widely applied, particularly in the areas of heat management and electronic packaging owing to its high thermal and electrical conductivities, which can be further improved together with improvements in mechanical properties by compositing it with carbon nanotubes (CNTs). However, because hydrophobic CNTs are hardly dispersible in aqueous solutions, additional intense acid treatment or the addition of dispersants is required for their dispersion. Moreover, previous studies have reported that these methods suffer from deterioration of composite material performance through the destruction of the CNT surface or the inclusion of dispersants into the plating. Therefore, in this study, the electrodeposition of a Cu/CNT composite in a non-aqueous solvent that can disperse CNTs without any additional treatment is investigated. The experimental results show that it is possible to deposit Cu from a N-methyl-2-pyrrolidone containing copper iodide and potassium iodide. Furthermore, Cu/CNT composite platings containing CNTs up to 0.12 mass% were prepared by constant current electrolysis, and applying pulse electrolysis can increase the CNTs content up to 0.22 mass%.

DOI： 10.3390/coatings13040802

Effect of nanostructure, porosity and extent of oxidation on soot reactivity 査読有り国際共著国際誌

Fang Mingming, Zhao Pengcheng, Ma Yongzhi, Hagio Takeshi, Li Xinling

FULLERENES NANOTUBES AND CARBON NANOSTRUCTURES 31 巻 ( 3 ) 頁： 241 - 254 2023年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Fullerenes Nanotubes and Carbon Nanostructures

Oxidation evolutions of structure, porosity and reactivity properties of four model carbons (PU, S160, N330 and R250) with different initial reactivity were studied. Results showed that changes in the porosity and nanostructure properties instead of initial properties significantly affected the soot reactivity during the soot oxidation process. Two high-reactivity soot surrogate samples, i.e., PU and S160, initially presented turbostratic disordered crystallites, resulting in higher reactivity at the early oxidation stage. Oxidation mainly proceeded inwardly in a peeling fashion, and more disordered internal crystallites were exposed after oxidized, slightly increasing the reactivity of PU and S160. Two low reactivity soot surrogate samples, i.e., N330 and R250, initially exhibited the typical core–shell structure. The oxidation rates of N330 and R250 were lower than that of PU and S160 due to more ordered exterior crystallites and less surface oxygen content at the early oxidation stage. Once oxygen penetrated the particle core, many pores were generated. Next, the particle became hollow through internal burning of the more reactive internal carbon at the late oxidation stage. After 40% burnoff, these hollow structures promoted oxidation in both outward and inward directions. Therefore, oxidation rates of N330 and R250 significantly increased.

DOI： 10.1080/1536383X.2022.2139371

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