Faculty Profiles - Chiyu NAKANO

Papers - Chiyu NAKANO

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Factors Influencing on Stability of Water-in-crude Oil (W/O) Emulsions

中野知佑, 池内孝夫, 進藤隆世志

Journal of the Japan Petroleum Institute (Web) 60 ( 5 ) 2017

Exploring the structural and optical properties in Cs<inf>3</inf>Fe<inf>2</inf>Cl<inf>9</inf> perovskite through ruthenium doping

Thiri Htun, Hytham Elbohy, Hiroo Suzuki, Kazumasa Horigane, Chiyu Nakano, Takeshi Nishikawa, Aung Ko Ko Kyaw, Yasuhiko Hayashi

Journal of Materials Science: Materials in Electronics 36 ( 5 ) 2025.2

Publishing type：Research paper (scientific journal)

Lead-free inorganic perovskites, such as Cs3Fe2Cl9, have emerged as promising alternatives to address the challenges of toxicity and instability issues. However, the wide bandgap of Cs3Fe2Cl9 limits its applicability in some applications. In this study, we systematically investigate the influence of ruthenium (Ru) doping on the structural and optical properties of Cs3Fe2Cl9 perovskite with the various doping concentrations (0%, 5%, 20%, 50%, 70% and 100%). Comprehensive characterization was performed through X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–Vis spectroscopy, and scanning electron microscopy (SEM). Structural analysis revealed a phase transition from Cs3Fe2Cl9 (hexagonal structure) at 0% Ru doping to Cs2RuCl6 (cubic structure) at 100% Ru doping. Notably, ruthenium was successfully replaced into the pristine Cs3Fe2Cl9 perovskite due to the similar ionic radii of Fe and Ru. Optical measurements confirmed a significant bandgap reduction from 2.29 eV for pristine Cs3Fe2Cl9 to 1.79 eV at 100% Ru doping, correlating with the formation of single crystals. This tunable bandgap highlights the potential of Ru-doped Cs3Fe2Cl9 for next-generation optoelectronic applications, such as photovoltaics and photodetectors.

DOI： 10.1007/s10854-025-14382-1

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Enhanced capacity of aluminum-ion batteries by adjusting the average pore size of the porous carbon cathode

Yifeng Chen, Hiroo Suzuki, Shu Fukumoto, Chiyu Nakano, Takeshi Nishikawa, Shigeyuki Umezawa, Yasuhiko Hayashi

Journal of Materials Chemistry A 13 ( 11 ) 8052 - 8058 2025

Effects of aged microplastics on paddy soil properties and greenhouse gas emissions under laboratory aerobic conditions

Tian Zhang, Hiroaki Somura, Satoshi Akao, Nozomi Nakahara, Gamamada Liyanage Erandi Priyangika Perera, Chiyu Nakano, Morihiro Maeda

Soil Science and Plant Nutrition 1 - 10 2024.12

Gasification Behavior of Plant-Based Biomass and Its Application to the Manufacturing Process of Titanium Sulfides under Sulfur Partial Pressure

Ichiro Seki, Yuki Matsuoka, Chinami Matsuda, Noa Watanabe, Chiyu Nakano, Yuta Nishina

Materials Transactions 65 ( 10 ) 1310 - 1319 2024.10

Publishing type：Research paper (scientific journal)

Metallic titanium ingots can be manufactured via thermal decomposition of titanium sulfides. In our previous study, we thermodynamically and experimentally investigated the phase relationship of titanium oxides and sulfides under carbothermic and hydrogen gas flow atmospheres, that is, non-carbothermic atmospheres. Recently, carbon neutral processes for metallurgical processes that use plant-based biomass, which plays essential roles in environmental protection, have been focused. In this study, the gasification behavior of biomass was investigated by thermal gravimetry-differential thermal analysis, and the deoxidization and sulfurization behaviors that generate titanium sulfides were also experimentally investigated. The gasification behavior differs according to the type of biomass, including the amounts of H2O in the biomass. The reaction temperature for CO2 generation decreased with increasing biomass H2O content. However, the total amounts of generated gas ratios of H2O/CO2 were hardly different, and the partial pressures of oxygen during gasification were also fixed as a function of temperature. The products were analyzed using X-ray diffractometry and identified as titanium disulfide (TiS2), similar to a carbothermic process.

DOI： 10.2320/matertrans.MT-M2023220

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Engineering Zeolitic-Imidazolate-Framework-Derived Mo-Doped Cobalt Phosphide for Efficient OER Catalysts

Mohammad Atiqur Rahman, Ze Cai, Zannatul Mumtarin Moushumy, Ryuta Tagawa, Yoshiharu Hidaka, Chiyu Nakano, Md. Saidul Islam, Yoshihiro Sekine, Yuta Nishina, Shintaro Ida, Shinya Hayami

ACS Omega 2024.8

Lead-free iron-doped Cs₃Bi₂Br₉ perovskite with tunable properties

Thiri Htun, Amr Elattar, Hytham Elbohy, Kosei Tsutsumi, Kazumasa Horigane, Chiyu Nakano, Xiaoyu Gu, Hiroo Suzuki, Takeshi Nishikawa, Aung Ko Ko Kyaw, Yasuhiko Hayashi

RSC Advances 14 ( 32 ) 23177 - 23183 2024.7

Enhanced OH⁻ conductivity from 3D alkaline graphene oxide electrolytes for anion exchange membrane fuel cells

Nonoka Goto, Mohammad Atiqur Rahman, Md Saidul Islam, Ryuta Tagawa, Chiyu Nakano, Muhammad Sohail Ahmed, Yoshihiro Sekine, Yuta Nishina, Shintaro Ida, Shinya Hayami

Energy Advances 3 ( 5 ) 1047 - 1053 2024.4

Publishing type：Research paper (scientific journal)

A promising green energy technology, anion exchange membrane fuel cells (AEMFCs) offer several advantages over proton exchange membrane fuel cells (PEMFCs), including lower cost, higher durability, and improved effectiveness. However, the widespread commercialization of AEMFCs has been hindered by the lack of low-cost, high-conductivity anion-exchange membranes (AEMs). This work reports the fabrication of a high-conductivity OH− ion exchange membrane using simple freeze-drying of graphene oxide at pH = 11 (3DGO11). At 25 °C and 100% RH conditions, the resulting membrane exhibits a through-plane hydroxide ion conductivity of 1.93 × 10−4 S cm−1 and an in-plane conductivity of 3.74 × 10−2 S cm−1. This high conductivity is attributed to the high porosity and multi-directional ion transport pathways created by the three-dimensional alkaline graphene oxide structure. These findings suggest a route for the development of cost-effective and high-performance AEMFCs.

DOI： 10.1039/d4ya00059e

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Phosphorus Release from Agricultural Drainage Sediments with Iron-Added Sediment Microbial Fuel Cells

Gamamada Liyanage Erandi Priyangika Perera, Morihiro Maeda, Satoshi Akao, Hiroaki Somura, Chiyu Nakano, Yuta Nishina

Journal of Water and Environment Technology 22 ( 2 ) 75 - 91 2024

Effects of Sediment Microbial Fuel Cells on CH<sub>4</sub> and CO<sub>2</sub> Emissions from Straw Amended Paddy Soil

Adhena Tesfau Bekele, Morihiro Maeda, Satoshi Akao, Hiroaki Somura, Chiyu Nakano, Yuta Nishina

Journal of Water and Environment Technology 22 ( 6 ) 271 - 285 2024

Benzophenone: A Small Molecule Additive for Enhanced Performance and Stability of Inverted Perovskite Solar Cells. International journal

Hytham Elbohy, Hiroo Suzuki, Takeshi Nishikawa, Thiri Htun, Kosei Tsutsumi, Chiyu Nakano, Aung Ko Ko Kyaw, Yasuhiko Hayashi

ACS applied materials & interfaces 2023.9

Language：English Publishing type：Research paper (scientific journal)

In this study, we investigated the impact of benzophenone (BP), a small molecule additive, on the performance and stability of inverted perovskite solar cells (PSCs). Specifically, we introduced BP into the perovskite precursor solution of FAPbI3 to fabricate PSCs with an ITO/PEDOT:PSS/BP:FAPbI3/PCBM/C60/PCB/Ag architecture. The incorporation of BP with an optimum concentration of 2 mg mL-1 significantly enhanced the power conversion efficiency (PCE) of the inverted PSC from 13.12 to 18.84% with negligible hysteresis. Notably, the BP-based PSCs retained ∼90% of their initial PCE after being stored in ambient air with 30% relative humidity at 25 °C for 700 h. In contrast, control devices showed rapid degradation, retaining only 30% of their initial value within 300 h under the same conditions. We attributed the superior performance and stability of the BP-based PSCs to the grain boundary passivation of the perovskite film. The improvement was mainly attributed to the intermolecular interaction between the O-donor Lewis base BP material and both Pb2+ and FA+ in FAPbI3. This effectively suppresses trap-assisted recombination and promotes the conversion of the δ-phase to photoactive and stable α-phase FAPbI3. Overall, our findings suggest that BP is a promising additive for improving the performance and stability of inverted PSCs.

DOI： 10.1021/acsami.3c09835

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原材料と焼成温度の異なるバイオ炭の酸化処理が土壌からの一酸化二窒素放出に及ぼす影響 Reviewed

増倉勇樹, 前田守弘, 中野知佑, 宗村広昭, 山根信三, 仁科勇太

日本土壌肥料学雑誌 94 ( 4 ) 245 - 253 2023.8

Intermediate State between MoSe2 and Janus MoSeS during Atomic Substitution Process

Hiroo Suzuki, Yijun Liu, Masaaki Misawa, Chiyu Nakano, Yingzhe Wang, Ryo Nakano, Kentaro Ishimura, Kenji Tsuruta, Yasuhiko Hayashi

NANO LETTERS 23 ( 10 ) 4533 - 4540 2023.5

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Janus transition metal dichalcogenides (TMDCs), with dissimilar chalcogen atoms on each side of TMDCs, have garnered considerable research attention because of the out-of-plane intrinsic polarization in monolayer TMDCs. Although a plasma process has been proposed for synthesizing Janus TMDCs based on the atomic substitution of surface atoms at room temperature, the formation dynamics and intermediate electronic states have not been completely examined. In this study, we investigated the intermediate state between MoSe2 and Janus MoSeS during plasma processing. Atomic composition analysis and atomic scale structural observations revealed the intermediate partially substituted Janus (PSJ) structure. Combined with theoretical calculations, we successfully clarified the characteristic Raman modes in the intermediate PSJ structure. The PL exhibited discontinuous transitions that could not be explained by the theoretical calculations. These findings will contribute toward understanding the formation process and electronic-state modulation of Janus TMDCs.

DOI： 10.1021/acs.nanolett.3c00972

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Dynamic nuclear polarization - nuclear magnetic resonance for analyzing surface functional groups on carbonaceous materials

Hideka Ando, Katsuaki Suzuki, Hironori Kaji, Takashi Kambe, Yuta Nishina, Chiyu Nakano, Kazuma Gotoh

CARBON 206 84 - 93 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Dynamic nuclear polarizing (DNP) technique in nuclear magnetic resonance (NMR) is a powerful tool for a microanalysis. Nevertheless, it has not been applied to analyses of carbon materials such as graphene oxide (GO) and amorphous carbon effectively because of the electroconductivity and microwave absorption of the carbon, which attenuate the enhancement effect of DNP. For this study, we applied DNP-NMR to analyses of surface functional groups on GO and sucrose-derived carbon to evaluate the method. The 1H-13C cross-polarization magic-angle spinning (CP/MAS) DNP-NMR of a GO sample with AMUPol (polarizing agent) showed 2.2-times -enhanced peaks of 13C in epoxide, bonding to hydroxyl group, and in the graphene plane. Signal enhance-ment was raised by AMUPol radicals neighboring the surface functional groups and the graphene planes on GO particles, although attenuation by temperature rise must be considered. Furthermore, additional new peaks assigned to CH3 group on the GO particle surface were highly enhanced and were observed clearly only by the accumulations of 64 scans. For sucrose-derived carbon, DNP-NMR clearly revealed the -OH group on the carbon surface or carbon edge by heat treatment, which was not possible using conventional CP/MAS experiments. Cross Effect was found to be dominant in signal enhancements of the functional groups on GO and sucrose-derived carbon samples, except for the CH3 groups on GO. The CH3 enhancement is ascribed mainly to the Over-hauser effect or solid effect.

DOI： 10.1016/j.carbon.2023.02.010

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Iron-Added Sediment Microbial Fuel Cells to Suppress Phosphorus Release from Sediment in an Agricultural Drainage

Gamamada Liyanage Erandi Priyangika Perera, Morihiro Maeda, Hiroaki Somura, Chiyu Nakano, Yuta Nishina

Journal of Water and Environment Technology 21 ( 5 ) 237 - 248 2023

Publishing type：Research paper (scientific journal)

Phosphorus (P) release from sediment caused eutrophication in Kojima Lake, Japan. The efficiency of iron-added sediment microbial fuel cells (SMFCs) in regulating P release from agricultural drainage sediment was investigated in this study. Surface sediment collected from an agricultural drainage canal flowing into Kojima Lake was mixed with iron oxide (Fe2O3) or amorphous iron oxyhydroxide (FeOOH) at 50 mmol kg−1. A 14.6-cm high acrylic pipe was filled with 80 mL of deionized water after 130 g of sediment was placed. A 3 x 3 cm graphite felt was used for the anode in a dual chamber SMFC, while a carbon rod was used for the cathode. Three treatments: No Fe, Fe2O3, and FeOOH, were operated for 408 h under open or closed circuit conditions. Results showed that FeOOH addition lowered P release from sediment regardless of SMFC operational conditions, suggesting that higher P adsorption by FeOOH may mask the effect of SMFCs. Fe2O3 did not reduce total P concentration in the overlying water. In addition, electricity generation was not enhanced by Fe-added SMFCs. Although SMFCs increased sedimentary redox potential, P release was not suppressed by the SMFC operation, indicating that organic P would be released by SMFCs from P-rich sediment.

DOI： 10.2965/JWET.23-040

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OPTIMIZATION OF RECOVERY AND QUALITY OF SECOND GENERATION BIO DIESEL FUEL PRODUCED FROM PALM ACID OIL BY COMPOSITE BASE METAL CATALYSTS SUPPORTED ON PARTICULATE SILICA GEL

Hirofumi Noge, Chiyu Nakano, Hasannuddin Abdul Kadir, Wira Jazair Yahya, Yoshie Ueno

European Biomass Conference and Exhibition Proceedings 891 - 895 2023

Publishing type：Research paper (international conference proceedings)

The main purpose of this research is to convert palm acid oil (PAO) into high quality 2nd generation biodiesel fuel (2ndgen.BDF). In this study, we aim to promote decarboxylation (DCX), decarbonylation (DCN), hydrodeoxygenation (HDO), and catalytic cracking (CC) reactions under low pressure using a fixed bed reactor and a batch reactor. In order to proceed with the desired reaction smoothly, some inexpensive composite base metal catalysts supported on silica gel (SiO2) particles were used. Experiments conducted under atmospheric pressure using a fixed bed reactor showed that the recovery of 2ndgen.BDF was up to 50-60% and the acid number was reduced by 94%. In addition, saturated hydrocarbons of C10-C17 are generated in the main components. On the other hand, experiments with a batch reactor at an initial pressure of 0.1 MPa resulted in up to 93% recovery of 2ndgen.BDF and up to 72% reduction in acid value (AV). C15 and C17 saturated hydrocarbons were found to be the main products, indicating a selective reaction.

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吸水性ポリマーを用いた原油中水型（W/O）エマルジョンからの水分離 Reviewed

Chiyu Nakano, Yuta Takada, Yutaro Chida, Sumio Kato, Masataka Ogasawara, Takao Ikeuchi, Takayoshi Shindo

Journal of the Japan Petroleum Institute 61 ( 2 ) 59 - 71 2018

Publishing type：Research paper (scientific journal)

The removal of water from water-in-crude oil (W/O) emulsions was investigated using poly[(acrylic acid)-co-(sodium acrylate)] as water-absorptive-polymer (WAP) at 15°C-70°C and under 0.1-1.5 MPa using a batch or a flow separation system. The W/O emulsions with water content of 1-5 mass% were prepared from Upper Zakum crude oil reserved at a domestic oil stockpiling base and distilled water. In each separation system, water absorption rates of both granular and fibrous WAP from W/O emulsions under ambient conditions were much faster than that of zeolite 4A, indicating an effectiveness of WAP for water separation. Removal of water from W/O emulsions was improved at high temperatures (50°C-70°C) and under high pressures (1.0-1.5 MPa). The regeneration of used WAP was achieved by rinsing them in toluene followed by drying. These results indicate that absorption of water from W/O emulsion using WAP is a potential physical demulsification methods, e.g., centrifugal separation, thermal treatment, and gravitational sedimentation without using chemical demulsifier.

DOI： 10.1627/jpi.61.59

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