Royal Society of Chemistry (RSC) Acta Medica Okayama 2050-7488 13 11 2025 Enhanced capacity of aluminum-ion batteries by adjusting the average pore size of the porous carbon cathode 8052 8058 EN Yifeng Chen Graduate School of Environmental, Life, Natural Science, and Technology, Okayama University Hiroo Suzuki Graduate School of Environmental, Life, Natural Science, and Technology, Okayama University Shu Fukumoto Graduate School of Environmental, Life, Natural Science, and Technology, Okayama University Chiyu Nakano Department of Comprehensive Technical Solutions, Okayama University Takeshi Nishikawa Graduate School of Environmental, Life, Natural Science, and Technology, Okayama University Shigeyuki Umezawa Seiwa Electric Mfg. Co., Ltd Yasuhiko Hayashi Graduate School of Environmental, Life, Natural Science, and Technology, Okayama University Lithium-ion batteries (LIBs) are widely used but with the increasing scarcity and uneven distribution of global lithium resources, there is a need to explore alternative battery technologies. Due to its abundance, low cost, and high theoretical capacity, aluminum is a strong candidate for metal anodes, making aluminum-ion batteries (AIBs) an area of considerable interest. Current mainstream research focuses on ionic liquid electrolytes, which offer a wide electrochemical window and high ionic conductivity. Carbon materials are ideal cathode candidates due to their low cost, abundance, and high voltage platform. AIBs using carbon materials typically exhibit low discharge capacity. This study addressed the challenge of improving the discharge capacity of carbon-based cathodes in AIBs. By using porous carbon (PC) materials with varying specific surface areas, average pore sizes, and total pore volumes as cathodes, average pore size was found to impact capacity. This contradicts the contention that larger specific surface areas result in higher capacities. There is a key difference in ion behavior: whereas aluminum chloride ions intercalate into layered graphite structures, they do not intercalate into PC materials but are adsorbed to the surface. By adjusting the average pore size, it is possible to increase the discharge capacity of AIBs, challenging the traditional emphasis on specific surface area. This research does not fully solve the problem of low discharge capacity in carbon-based cathodes, but provides a new perspective on the role of pore size in enhancing battery performance, offering valuable insights for future electrode design. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 2352-4928 51 2026 Optical spectroscopic evaluation on the acquisition of optimal sonication temperature for efficient liquid phase exfoliation of molybdenum disulfide 114910 EN Fatimah Az-Zahra Saravanan binti Abdullah School of Engineering and Physical Sciences, Heriot-Watt University Malaysia Wengnam Lee Foundation Center, Heriot-Watt University Malaysia Patrik Öhberg Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University Boontong Goh Low Dimensional Materials Research Center, Department of Physics, Faculty of Science, University of Malaya Wuyi Chong Photonics Research Center, University of Malaya Harith Ahmad Photonics Research Center, University of Malaya Yasuhiko Hayashi Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Takeshi Nishikawa Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Yuenkiat Yap Foundation Center, Heriot-Watt University Malaysia This work investigates how the sonication temperature affects the liquid phase exfoliation of MoS₂ using optical and morphological approach in attempt to acquire an optimal temperature for such process at ambient room conditions. In an ultrasonic bath, exfoliation was carried out at six different temperatures. UV-Vis, FTIR, Raman spectroscopy and SEM characterizations reveal that moderate room temperature range yield excellent results producing well-dispersed flakes with strong excitonic properties with mild oxidation. Higher temperatures cause substantial oxidation, deterioration and restacking while lower temperatures led to insufficient exfoliation and fragmented morphologies because of insufficient cavitation energy. The findings highlight the importance of temperature control in producing high quality nanosheets for scalable applications. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0957-4522 36 1 2024 Optical bandgap tuning in SnO2–MoS2 nanocomposites: manipulating the mass of SnO2 and MoS2 using sonochemical solution mixing 6 EN Chinkhai Ong School of Engineering and Physical Sciences, Heriot-Watt University Malaysia Weng Nam Lee Heriot-Watt Global College, Heriot-Watt University Malaysia Yee Seng Tan Sunway Biofunctional Molecules Discovery Centre, School of Medical and Life Sciences, Sunway University Patrik Ohberg School of Engineering and Physical Sciences, Institute of Photonics and Quantum Sciences, Heriot-Watt University Yasuhiko Hayashi Faculty of Environmental, Life, Natural Science and Technology, Okayama University Takeshi Nishikawa Faculty of Environmental, Life, Natural Science and Technology, Okayama University Yuenkiat Yap Heriot-Watt Global College, Heriot-Watt University Malaysia This study investigates controlled optical bandgap tuning through precise adjustment of the SnO2 and MoS2 mass in nanocomposites. A sonochemical solution mixing method, coupled with bath sonication, is employed for the preparation of SnO2–MoS2 nanocomposite. This approach allows for comprehensive characterization using UV–Vis FTIR, XRD, EDX, Raman spectroscopies, and FESEM, providing insights into morphology, chemical, and optical properties. Increasing the SnO2 mass leads to a linear decrease in the optical bandgap energy, from 3.0 to 1.7 eV. Similarly, increasing the MoS2 mass also results in a decrease in the optical bandgap energy, with a limitation of around 2.01 eV. This work demonstrates superior control over optical bandgap by manipulating the SnO2 mass compared to MoS2, highlighting the complexities introduced by MoS2 2D nanosheets during sonication. These findings hold significant value for optoelectronic applications, emphasizing enhanced control of optical bandgap through systematic mass manipulation. No potential conflict of interest relevant to this article was reported.

Informa UK Limited Acta Medica Okayama 0003-2719 58 2 2024 Influence of Dilution Upon the Ultraviolet-Visible Peak Absorbance and Optical Bandgap Estimation of Tin(IV) Oxide and Tin(IV) Oxide-Molybdenum(IV) Sulfide Solutions 196 212 EN Chin Khai Ong School of Engineering and Physical Sciences, Heriot-Watt University Malaysia Weng Nam Lee Heriot-Watt Global College, Heriot-Watt University Malaysia Mohammad Khalid Sunway Centre for Electrochemical Energy and Sustainable Technology (SCEEST), School of Engineering and Technology, Sunway University Muhammad Amirul Aizat Mohd Abdah Sunway Centre for Electrochemical Energy and Sustainable Technology (SCEEST), School of Engineering and Technology, Sunway University Patrik Ohberg Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University Ling Hong Lim Heriot-Watt Global College, Heriot-Watt University Malaysia Yasuhiko Hayashi Graduate School of Natural Science and Technology, Faculty of Engineering, Okayama University Takeshi Nishikawa Graduate School of Natural Science and Technology, Faculty of Engineering, Okayama University Yuenkiat Yap Heriot-Watt Global College, Heriot-Watt University Malaysia The study investigated the constraints associated with the dilution technique in determining the optical bandgap of nanoparticle dispersion and modified nanocomposites, utilizing ultraviolet-visible absorbance spectra and Tauc plot analysis. A case study involving SnO2 dispersion and SnO2-MoS2 nanocomposite solutions, prepared through the direct solution mixing method, was conducted to assess the implications of dilution upon the absorbance spectra and bandgap estimation. The results emphasize the considerable impact of the dilution technique on the measured optical bandgap, demonstrating that higher dilution factors lead to shift in bandgap values. Furthermore, the study highlights that dilution can induce variations in the average nanoparticle sizes due to agglomeration, thereby influencing bandgap estimation. In the context of nanocomposites, the interaction between SnO2 nanoparticles and exfoliated MoS2 nanosheets diminishes with increasing dilution, leading to the estimated optical bandgap being primarily attributable to SnO2 nanoparticles alone. These observations underscore the necessity for caution when employing the dilution technique for bandgap estimation in nanoparticles dispersion and nanocomposites, offering valuable insights for researchers and practitioners in the field. No potential conflict of interest relevant to this article was reported.

Royal Society of Chemistry Acta Medica Okayama 2046-2069 14 32 2024 Lead-free iron-doped Cs3Bi2Br9 perovskite with tunable properties 23177 23183 EN Thiri Htun Graduate School of Natural Science and Technology, Okayama University Amr Elattar Department of Chemistry, Faculty of Science, Ain Shams University Hytham Elbohy Physics Department, Faculty of Science, Damietta University Kosei Tsutsumi Graduate School of Natural Science and Technology, Okayama University Kazumasa Horigane Research Institute for Interdisciplinary Science, Okayama University Chiyu Nakano Advanced Science Research Center, Okayama University Xiaoyu Gu Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting and Department of Electronic & Electrical Engineering, Southern University of Science and Technology Hiroo Suzuki Graduate School of Natural Science and Technology, Okayama University Takeshi Nishikawa Graduate School of Natural Science and Technology, Okayama University Aung Ko Ko Kyaw Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting and Department of Electronic & Electrical Engineering, Southern University of Science and Technology Yasuhiko Hayashi Graduate School of Natural Science and Technology, Okayama University Perovskite based on cesium bismuth bromide offers a compelling, non-toxic alternative to lead-containing counterparts in optoelectronic applications. However, its widespread usage is hindered by its wide bandgap. This study investigates a significant bandgap tunability achieved by introducing Fe doping into the inorganic, lead-free, non-toxic, and stable Cs3Bi2Br9 perovskite at varying concentrations. The materials were synthesized using a facile method, with the aim of tuning the optoelectronic properties of the perovskite materials. Characterization through techniques such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, energy dispersive spectroscopy (EDS), and UV-vis spectroscopy was conducted to elucidate the transformation mechanism of the doping materials. The substitution process results in a significant change in the bandgap energy, transforming from the pristine Cs3Bi2Br9 with a bandgap of 2.54 eV to 1.78 eV upon 70% Fe doping. The addition of 50% Fe in Cs3Bi2Br9 leads to the formation of the orthorhombic structure in Cs2(Bi,Fe)Br5 perovskite, while complete Fe alloying at 100% results in the phase formation of CsFeBr4 perovskite. Our findings on regulation of bandgap energy and crystal structure through B site substitution hold significant promise for applications in optoelectronics. No potential conflict of interest relevant to this article was reported.

Springer Nature Acta Medica Okayama 1226-4601 24 1 2021 Synthesis and characterization of conductive flexible cellulose carbon nanohorn sheets for human tissue applications 18 EN Karthik Paneer Selvam Graduate School of Natural Science and Technology, Okayama University Taichi Nagahata Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Kosuke Kato Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Mayuko Koreishi Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Takeshi Nishikawa Graduate School of Natural Science and Technology, Okayama University Ayano Satoh Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Yasuhiko Hayashi Graduate School of Natural Science and Technology, Okayama University Background Conductive sheets of cellulose and carbon nanomaterials and its human skin applications are an interesting research aspect as they have potential for applications for skin compatibility. Hence it is needed to explore the effects and shed light on these applications. Method To fabricate wearable, portable, flexible, lightweight, inexpensive, and biocompatible composite materials, carbon nanohorns (CNHs) and hydroxyethylcellulose (HEC) were used as precursors to prepare CNH-HEC (Cnh-cel) composite sheets. Cnh-cel sheets were prepared with different loading concentrations of CNHs (10, 20 50,100mg) in 200mg cellulose. To fabricate the bio-compatible sheets, a pristine composite of CNHs and HEC was prepared without any pretreatment of the materials. Results The obtained sheets possess a conductivity of 1.83x10(-10)S/m and bio-compatible with human skin. Analysis for skin-compatibility was performed for Cnh-cel sheets by h-CLAT in vitro skin sensitization tests to evaluate the activation of THP-1 cells. It was found that THP-1 cells were not activated by Cnh-cel; hence Cnh-cel is a safe biomaterial for human skin. It was also found that the composite allowed only a maximum loading of 100mg to retain the consistent geometry of free-standing sheets of <100<mu>m thickness. Since CNHs have a unique arrangement of aggregates (dahlia structure), the composite is homogeneous, as verified by transmission electron microscopy (TEM) and, scanning electron microscopy (SEM), and other functional properties investigated by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), conductivity measurement, tensile strength measurement, and skin sensitization. Conclusion It can be concluded that cellulose and CNHs sheets are conductive and compatible to human skin applications. No potential conflict of interest relevant to this article was reported.

Nature Acta Medica Okayama 2045-2322 10 1 2020 Controlling Electronic States of Few-walled Carbon Nanotube Yarn via Joule-annealing and p-type Doping Towards Large Thermoelectric Power Factor 7307 EN May Thu Zar Myint Graduate School of Natural Science and Technology, Okayama University Takeshi Nishikawa Graduate School of Natural Science and Technology, Okayama University Kazuki Omoto Graduate School of Natural Science and Technology, Okayama University Hirotaka Inoue Graduate School of Natural Science and Technology, Okayama University Yoshifumi Yamashita Graduate School of Natural Science and Technology, Okayama University Aung Ko Ko Kyaw Department of Electrical and Electronic Engineering, Southern University of Science and Technology Yasuhiko Hayashi Graduate School of Natural Science and Technology, Okayama University Flexible, light-weight and robust thermoelectric (TE) materials have attracted much attention to convert waste heat from low-grade heat sources, such as human body, to electricity. Carbon nanotube (CNT) yarn is one of the potential TE materials owing to its narrow band-gap energy, high charge carrier mobility, and excellent mechanical property, which is conducive for flexible and wearable devices. Herein, we propose a way to improve the power factor of CNT yarns fabricated from few-walled carbon nanotubes (FWCNTs) by two-step method; Joule-annealing in the vacuum followed by doping with p-type dopants, 2,3,5,6-tetrafluo-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Numerical calculations and experimental results explain that Joule-annealing and doping modulate the electronic states (Fermi energy level) of FWCNTs, resulting in extremely large thermoelectric power factor of 2250 mu Wm(-1) K-2 at a measurement temperature of 423K. Joule-annealing removes amorphous carbon on the surface of the CNT yarn, which facilitates doping in the subsequent step, and leads to higher Seebeck coefficient due to the transformation from (semi) metallic to semiconductor behavior. Doping also significantly increases the electrical conductivity due to the effective charge transfers between CNT yarn and F4TCNQ upon the removal of amorphous carbon after Joule-annealing. No potential conflict of interest relevant to this article was reported.

IOP Publishing Acta Medica Okayama 2053-1591 7 5 2020 Synthesis of solvent-free conductive and flexible cellulose-carbon nanohorn sheets and their application as a water vapor sensor 056402 EN Karthik Paneer Selvam Graduate School of Natural Science and Technology, Okayama University Tomohiro Nakagawa Graduate School of Natural Science and Technology, Okayama University Tatsuki Marui Graduate School of Natural Science and Technology, Okayama University Hirotaka Inoue Graduate School of Natural Science and Technology, Okayama University Takeshi Nishikawa Graduate School of Natural Science and Technology, Okayama University Yasuhiko Hayashi Graduate School of Natural Science and Technology, Okayama University Carbon nanohorns (CNHs) are mixed with cellulose to make freestanding thin-film conductive sheets. CNHs, at different ratios (5, 10, 25, 50 wt%), form composites with cellulose (hydroxyethylcellulose). Freestanding cellulose-carbon nanohorn (CCN) sheets were fabricated using a 100 mu m-thick metal bar coater. Surfactants or any other chemical treatments to tailor the surface properties of CNHs were avoided to obtain composite sheets from pristine CNHs and cellulose. Utilizing the hygroscopic property of hydroxyethylcellulose and the electrical conductivity of CNHs paved a path to perform this experiment. The synthesis technique is simple, and the fabrication and drying of the sheets were effortless. As the loading concentration of CNH increased, the resistance, flexibility, and strength of the CCN composite sheets decreased. The maximum loading concentration possible to obtain a freestanding CCN sheet is 50 wt%. The resistance of the maximum loading concentration of CNH was 53 k omega. The response of the CCN sheets to water vapor was 4 s and recover time was 13 s, and it is feasible to obtain a response for different concentrations of water vapor. High-resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, resistance measurement, tensile strength measurement, and thermogravimetric analysis were used to investigate the mechanical, morphological, electrical, and chemical properties of the CCN sheets. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 95 23 2005 Opacity effect on extreme ultraviolet radiation from laser-produced tin plasmas EN Shinsuke Fujioka Hiroaki Nishimura Katsunobu Nishihara Akira Sasaki Atsushi Sunahara Tomoharu Okuno Nobuyoshi Ueda Tsuyoshi Ando Yezheng Tao Yoshinori Shimada Kazuhisa Hashimoto Michiteru Yamaura Keisuke Shigemori Mitsuo Nakai Keiji Nagai Takayoshi Norimatsu Takeshi Nishikawa Noriaki Miyanaga Yasukazu Izawa Kunioki Mima Opacity effects on extreme ultraviolet (EUV) emission from laser-produced tin (Sn) plasma have been experimentally investigated. An absorption spectrum of a uniform Sn plasma generated by thermal x rays has been measured in the EUV range (9-19 nm wavelength) for the first time. Experimental results indicate that control of the optical depth of the laser-produced Sn plasma is essential for obtaining high conversion to 13.5 nm-wavelength EUV radiation; 1.8% of the conversion efficiency was attained with the use of 2.2 ns laser pulses. No potential conflict of interest relevant to this article was reported.