Faculty Profiles - NISHINA Yuta

Papers - NISHINA Yuta

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Grafting-through functionalization of graphene oxide with cationic polymers for enhanced adsorption of anionic dyes and viruses

Ryota Kimura, Pilar Ferré-Pujol, Yuta Nishina

Carbon 238 2025.5

Publishing type：Research paper (scientific journal)

Graphene oxide (GO) is a sheet-like carbon material with abundant oxygen-containing functional groups on its surface. GO has been extensively studied as an adsorbent for heavy metals and organic compounds. However, effective strategies for negatively charged materials have yet to be established. This study aimed to synthesize composites of GO and cationic polymers for the selective adsorption of negatively charged materials; a challenge in this approach is the strong electrostatic interactions between GO and cationic polymers, which can lead to aggregation. This study addresses this issue by employing the grafting-through method. GO was initially modified with allylamine to introduce a polymerizable site, followed by radical polymerization to covalently bond polymers to the GO surface, effectively preventing aggregation. Adsorption experiments demonstrated that the GO-polymer composite selectively adsorbs anionic dye, such as methyl orange. Virus adsorption tests showed significantly enhanced performance compared to pristine GO. These results emphasize the critical role of controlled surface modification and charge manipulation in optimizing the adsorption performance of GO. This study establishes a simple and effective approach for synthesizing GO-cationic polymer composites, contributing to the development of advanced materials for water purification applications.

DOI： 10.1016/j.carbon.2025.120296

Reversible chemical modifications of graphene oxide for enhanced viral capture and release in water

Pilar Ferré-Pujol, Seiji Obata, Jésus Raya, Alberto Bianco, Hiroyuki Katayama, Takashi Kato, Yuta Nishina

Carbon 234 2025.3

Publishing type：Research paper (scientific journal)

Detecting low concentrations of viruses in sewage water is crucial for monitoring the spread of emerging viral diseases. However, current detection methods, which involve concentrating viruses using traditional materials such as gauze or cotton, have limitations in effectively accomplishing this task. This study demonstrates that graphene oxide (GO), a two-dimensional carbon material, possesses strong viral adsorption capabilities. However, it lacks efficiency for effective viral release. Therefore, we designed a series of new GO-based materials, which exhibited a viral adsorption similar to pristine GO, while significantly enhancing their release performance by attaching alkyl chains and hydrophilic functional groups. Among the synthesized materials, 1,8-aminooctanol grafted to GO (GO-NH2C8OH) has emerged as the most promising candidate, achieving a viral release rate higher than 50 %. This superior performance can be attributed to the synergistic effect of the alkyl chain and the terminal OH group, which enhances both its affinity for viruses and water dispersibility. Furthermore, we have successfully applied GO-NH2C8OH in a new protocol for concentrating viruses from sewage wastewater. This approach has demonstrated a 200-fold increase in virus concentration, allowing PCR detection of this type of pathogens present in wastewater below the detection limit by direct analysis, underscoring its significant potential for virus surveillance.

DOI： 10.1016/j.carbon.2025.120015

Graphene Oxide as a Self‐Carbocatalyst to Facilitate the Ring‐Opening Polymerization of Glycidol for Efficient Polyglycerol Grafting

Yajuan Zou, Kentaro Ohkura, Israel Ortiz‐Anaya, Ryota Kimura, Alberto Bianco, Yuta Nishina

Chemistry – A European Journal 2025.1

Publishing type：Research paper (scientific journal) Publisher：Wiley

Abstract

Grafting carbon‐based nanomaterials (CNMs) with polyglycerol (PG) improves their application potentials in biomedicine and electronics. Although “grafting from” method offers advantages over “grafting to” one in terms of operability and versatility, little is known about the reaction process of glycidol with the surface groups onto CNMs. By using graphene oxide (GO) as a multi‐functional model material, we examined the reactivity of the surface groups on GO toward glycidol molecules via a set of model reactions. We reveal that carboxyl groups spontaneously react with the epoxide ring with no need of catalyst, while GO catalyzes the reactions of hydroxyl groups with the epoxide of glycidol. In addition, the hydroxyl group of glycidol can open the epoxide in the basal plane of GO. The subsequent polymerization of PG is supposed to propagate at the primary and/or the secondary hydroxyl groups, generating a ramified PG macromolecule with random branch‐on‐branch topology. In addition, ketones, benzyl esters and aromatic ethers are found not to react with glycidol even in the presence of GO, while the aldehydes are easily oxidized into carboxyl groups under ambient condition, behaving then as the carboxyl groups. Our findings pose the foundation for understanding the polymerization mechanism of PG on CNMs.

DOI： 10.1002/chem.202404400

Electrochemical exfoliation of graphite using aqueous ammonium hydrogen carbonate solution and the ability of the exfoliated product as a hydrogen production electrocatalyst support International journal

Ryuichi Maekawa, Hirooki Kajiwara, Yuto Washiyama, Yasushi Nishikawa, Naoto Kuwamura, Toshinori Okura, Yuta Nishina, Hideki Hashimoto

Heliyon 10 ( 23 ) e40751 - e40751 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier BV

Electrochemical exfoliation of graphite has attracted much attention as a practical mass production of two-dimensional graphene-like materials. There is an increasing desire to find new and improved methods to create unique exfoliated products with excellent functionality. We used aqueous ammonium hydrogen carbonate solution as a new electrolyte for anodic oxidative exfoliation of graphite. The exfoliated product has a porous two-dimensional structure, and it can be dispersed in water for over five years. The oxidized and defected porous surface serves as an ideal support for molecular metal complexes, effectively functioning as heterogeneous electrocatalysts for hydrogen production.

DOI： 10.1016/j.heliyon.2024.e40751

Control of the electronic and optical properties of aminoxyl radicals via boron complexation. International journal

Takuma Kuroda, Peiyuan Yang, Marika Nakamura, Risa Hyakutake, Hiroki Fukumoto, Toshiyuki Oshiki, Yuta Nishina, Koichiro Masada, Takahiro Sasamori, Yosihiyuki Mizuhata, Kazuya Kubo, Ryo Inoue, Tomohiro Agou

Dalton transactions (Cambridge, England : 2003) 2024.11

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

Stable radicals have attracted increasing attention in recent years because of their unique electronic and optical characteristics. Aminoxyl radicals are one of the most widely studied stable radicals to date, but their applications in opto-functional materials have yet to be explored in detail. Our group previously reported the boron complexes of aminoxyl radicals exhibit near-infrared (NIR) absorption. In this work, an aminoxyl radical without boron-complexation was synthesized to elucidate the effects of boron coordination on the properties of the aminoxyl radicals. The results of electron spin resonance spectroscopy, ultraviolet-visible-NIR absorption measurements, and density functional theory calculations indicated that boron complexation facilitated spin delocalization over the radical π-frameworks. Furthermore, a π-extended aminoxyl radical-boron complex exhibited a significant wavelength-shift to longer wavelengths in the NIR-II absorption region, thereby reflecting its larger π-conjugated radical skeleton.

DOI： 10.1039/d4dt02973a

Mass Production of Graphene Oxide Beyond the Laboratory: Bridging the Gap Between Academic Research and Industry International journal

Yuta Nishina

ACS Nano 18 ( 49 ) 33264 - 33275 2024.11

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)

The mass production of graphene oxide (GO) has garnered significant attention in recent years due to its potential applications in various fields, from materials science to biomedicine. Graphene, known for its unique properties, such as high conductivity and mechanical strength, has been extensively studied. However, traditional production methods such as the exfoliation of graphite with scotch tape are not suitable for large-scale production. This has led to an increased focus on GO as a viable alternative to graphene production. Nonetheless, challenges, including the optimization of oxidation processes, the control of structural uniformity, and the reproducibility of production, have not been solved so far. This review critically examines GO production advancements by analyzing experimental and mechanistic studies to identify significant developments that enable high-yield and reproducible methods suitable for industrial-scale production. Special attention is given to oxidation techniques and postsynthesis purification and storage, with a focus on controlled oxidation to achieve homogeneous and single-layer GO. Through this lens, the review outlines the path forward for the industrialization of GO, aiming to bridge the gap between academic research and industrial production.

DOI： 10.1021/acsnano.4c13297

Biocompatibility of Water-Dispersible Pristine Graphene and Graphene Oxide Using a Close-to-Human Animal Model: A Pilot Study on Swine. International journal

Paola Nicolussi, Giovannantonio Pilo, Maria Giovanna Cancedda, Guotao Peng, Ngoc Do Quyen Chau, Alejandro De la Cadena, Renzo Vanna, Yarjan Abdul Samad, Tanweer Ahmed, Jeremia Marcellino, Giuseppe Tedde, Linda Giro, Acelya Ylmazer, Federica Loi, Gavina Carta, Loredana Secchi, Silvia Dei Giudici, Simona Macciocu, Dario Polli, Yuta Nishina, Ciriaco Ligios, Giulio Cerullo, Andrea Ferrari, Alberto Bianco, Bengt Fadeel, Giulia Franzoni, Lucia Gemma Delogu

Advanced healthcare materials e2401783 2024.10

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

Graphene-based materials (GBMs) are of considerable interest for biomedical applications, and the pilot study on the toxicological and immunological impact of pristine graphene (GR) and graphene oxide (GO) using swine as a close-to-human provides valuable insights. First, ex vivo experiments are conducted on swine blood cells, then GBMs are injected intraperitoneally (i.p.) into swine. Hematological and biochemical analyses at various intervals indicate that neither GO nor GR cause systemic inflammation, pro-coagulant responses, or renal or hepatic dysfunction. Importantly, no systemic toxicity is observed. Analysis of a panel of 84 immune-related genes shows minimal impact of GO and GR. The animals are sacrificed 21 days post-injection, and transient absorption imaging and Raman mapping show the presence of GO and GR in the mesentery only. Histological evaluation reveals no signs of alterations in other organs. Thus, clusters of both materials are detected in the mesentery, and GO aggregates are surrounded only by macrophages with the formation of granulomas. In contrast, modest local reactions are observed around the GR clusters. Overall, these results reveal that i.p. injection of GBMs resulted in a modest local tissue reaction without systemic toxicity. This study, performed in swine, provides essential guidance for future biomedical applications of graphene.

DOI： 10.1002/adhm.202401783

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

Investigating the radical properties of oxidized carbon materials under photo-irradiation: behavior of carbon radicals and their application in catalytic reactions. International journal

Md Razu Ahmed, Israel Ortiz Anaya, Yuta Nishina

Chemical communications (Cambridge, England) 60 ( 76 ) 10544 - 10547 2024.9

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

Oxidized carbon materials have abundant surface functional groups and customizable properties, making them an excellent platform for generating radicals. Unlike reactive oxygen species such as hydroxide or superoxide radicals that have been reported previously, oxidized carbon also produces stable carbon radicals under photo-irradiation. This has been confirmed through electron spin resonance. Among the various oxidized carbon materials synthesized, graphene oxide shows the largest number of carbon radicals when exposed to blue LED light. The light absorption capacity, high surface area, and unique structural characteristics of oxidized carbon materials offer a unique function for radical-mediated oxidative reactions.

DOI： 10.1039/d4cc03101f

State change of Na clusters in hard carbon electrodes and increased capacity for Na-ion batteries achieved by heteroatom doping

Hideka Ando, Kenjiro Hashi, Shinobu Ohki, Yoshikiyo Hatakeyama, Yuta Nishina, Norihiro Kowata, Takahiro Ohkubo, Kazuma Gotoh

Carbon Trends 16 100387 - 100387 2024.9

Light-Responsive and Antibacterial Graphenic Materials as a Holistic Approach to Tissue Engineering. International journal

Andrea Ferreras, Ana Matesanz, Jabier Mendizabal, Koldo Artola, Yuta Nishina, Pablo Acedo, José L Jorcano, Amalia Ruiz, Giacomo Reina, Cristina Martín

ACS nanoscience Au 4 ( 4 ) 263 - 272 2024.8

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

While the continuous development of advanced bioprinting technologies is under fervent study, enhancing the regenerative potential of hydrogel-based constructs using external stimuli for wound dressing has yet to be tackled. Fibroblasts play a significant role in wound healing and tissue implants at different stages, including extracellular matrix production, collagen synthesis, and wound and tissue remodeling. This study explores the synergistic interplay between photothermal activity and nanomaterial-mediated cell proliferation. The use of different graphene-based materials (GBM) in the development of photoactive bioinks is investigated. In particular, we report the creation of a skin-inspired dressing for wound healing and regenerative medicine. Three distinct GBM, namely, graphene oxide (GO), reduced graphene oxide (rGO), and graphene platelets (GP), were rigorously characterized, and their photothermal capabilities were elucidated. Our investigations revealed that rGO exhibited the highest photothermal efficiency and antibacterial properties when irradiated, even at a concentration as low as 0.05 mg/mL, without compromising human fibroblast viability. Alginate-based bioinks alongside human fibroblasts were employed for the bioprinting with rGO. The scaffold did not affect the survival of fibroblasts for 3 days after bioprinting, as cell viability was not affected. Remarkably, the inclusion of rGO did not compromise the printability of the hydrogel, ensuring the successful fabrication of complex constructs. Furthermore, the presence of rGO in the final scaffold continued to provide the benefits of photothermal antimicrobial therapy without detrimentally affecting fibroblast growth. This outcome underscores the potential of rGO-enhanced hydrogels in tissue engineering and regenerative medicine applications. Our findings hold promise for developing game-changer strategies in 4D bioprinting to create smart and functional tissue constructs with high fibroblast proliferation and promising therapeutic capabilities in drug delivery and bactericidal skin-inspired dressings.

DOI： 10.1021/acsnanoscienceau.4c00006

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

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 9 ( 34 ) 36114 - 36121 2024.8

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)

Designing a cheap, competent, and durable catalyst for the oxygen evolution reaction (OER) is exceedingly necessary for generating oxygen through a water-splitting reaction. In this project, we have designed a ZIF-67-originated molybdenum-doped cobalt phosphide (CoP) using a simplistic dissolution-regrowth method using Na2MoO4 and a subsequent phosphidation process. This leads to the formation of an exceptional hollow nanocage morphology that is useful for enhanced catalytic activity. Metal-organic frameworks, especially ZIF-67, can be used both as a template and as a metal (cobalt) precursor. Molybdenum-doped CoP was fabricated through a two-step synthesis process, and the fabricated Mo-doped CoP showed excellent catalytic activity during the OER with a lower value of overpotential. Furthermore, the effect of the Mo amount on the catalytic activity has been explored. The best catalyst (CoMoP-2) showed an onset potential of around 1.49 V at 10 mA cm-2 to give rise to a Tafel slope of 62.1 mV dec-1. The improved catalytic activity can be attributed to the increased porosity and surface area of the resultant catalyst.

DOI： 10.1021/acsomega.4c00403

Size‐Dependent Magnetic Responsiveness of a Photonic Crystal of Graphene Oxide Nanosheets International journal

Daisuke Ogawa, Yuta Nishina, Koki Sano

ChemPlusChem 89 ( 12 ) e202400449 2024.8

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

A magnetically responsive photonic crystal of colloidal nanosheets can exhibit a controllable structural color, offering diverse potential applications. In this study, we systematically investigated how the lateral sizes of graphene oxide (GO) nanosheets affect their magnetic responsiveness in a photonic system. Contrary to the prediction that larger lateral sizes of nanosheets would be more responsive to an applied magnetic field based on the magnetic energy of anisotropic materials, we discovered that GO nanosheets with larger lateral sizes in the photonic system scarcely responded to a 12 T magnetic field. The lack of magnetic response may be due to the strongly restricted rotational motion of GO nanosheets by mutual electrostatic forces. In contrast, GO nanosheets with medium lateral sizes readily responded to the 12 T magnetic field, forming a uniaxially oriented structure that resulted in a vivid structural color. However, smaller GO nanosheets displayed a less vivid structural color, possibly because of less structural ordering of GO nanosheets. Finally, we found that the photonic crystal of GO nanosheets with optimized lateral sizes responded effectively to the 12 T magnetic field across various GO concentrations, resulting in a vivid and tunable structural color.

DOI： 10.1002/cplu.202400449

Ordered Carbonaceous Framework Synthesized from Hexaazatrinaphthylene with Enediyne Groups via Solid-State Bergman Cyclization Reaction International journal

Yuki Sano, Ryojun Toyoda, Koki Chida, Takeharu Yoshii, Hirotomo Nishihara, Yuta Nishina, Daisuke Asanoma, Shinya Takaishi, Kunihisa Sugimoto, Ryota Sakamoto

ACS Applied Materials & Interfaces 16 ( 32 ) 42615 - 42622 2024.8

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)

Porous materials synthesized through bottom-up approaches, such as metal-organic frameworks and covalent organic frameworks, have attracted attention owing to their design flexibility for functional materials. However, achieving the chemical and thermal stability of these materials for various applications is challenging considering the reversible coordination bonds and irreversible covalent bonds in their frameworks. Thus, ordered carbonaceous frameworks (OCFs) emerge as a promising class of bottom-up materials with good periodicity, thermal and chemical stability, and electrical conductivity. However, a few OCFs have been reported owing to the limited range of precursor molecules. Herein, we designed a hexaazatrinaphthylene-based molecule with enediyne groups as a precursor molecule for synthesizing an OCF. The solid-state Bergman cyclization of enediyne groups at a low temperature formed a microporous polymer and an OCF, exhibiting redox activity and demonstrating their potential for electrochemical applications. The microporous polymer was used as an active material in sodium-ion batteries, while the OCF was used as an electrochemical capacitor. These findings illustrate the utility of the Bergman cyclization reaction for synthesizing microporous polymers and OCFs with a customizable functionality for broad applications.

DOI： 10.1021/acsami.4c06959

Diverse Hierarchical Meso/Nanoporous Pt Film Electrocatalysts Prepared via Hydrogen Adsorption-Assisted Dynamic Soft Templating International journal

Shunsuke Shiba, Ayano Ogata, Shin Matsushita, Osamu Niwa, Masashi Kunitake, Masanobu Matsuguchi, Masato Komoda, Yuta Nishina

Langmuir 40 ( 31 ) 16349 - 16360 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society (ACS)

In this study, we present an innovative approach for creating hierarchical meso/nanoporous Pt films using dynamic soft templating. The fabrication process, called dynamic soft templating, involves Pt electrodeposition within a specialized bicontinuous microemulsion (BME) system characterized by a sophisticated three-dimensional network comprising water and oil phases, surfactants, and cosurfactants. Pt electrodeposition exclusively occurs in the water phase of the BME. This results in a porous Pt film exhibiting a nanostructure mirroring the oil solution/water solution nanostructure (solution/solution structure) of the BME, the size of which can be tailored by adjusting the BME composition. Through a simultaneous interplay of Pt electrodeposition and overpotential deposition of hydrogen (H-OPD, dissociative adsorption of water), potential-dependent Pt mesostructures are dynamically shaped. As a result, we achieve diverse morphologies in the form of hierarchical meso/nanoporous Pt films. The potential applications of the films are evaluated as electrocatalysts for the methanol oxidation reaction (MOR), and it was found that the electrocatalytic performances seem to be sensitive to nanoporosity and not relevant to mesoporosity.

DOI： 10.1021/acs.langmuir.4c01567

Enhanced thermal conductivity of fluids by percolating high-concentration few-layer graphene

Keiko Ishii, Takahiro Ogiyama, Koji Fumoto, Yuta Nishina

Applied Physics Letters 125 ( 2 ) 2024.7

Publishing type：Research paper (scientific journal) Publisher：AIP Publishing

High-performance and small-sized heat exchangers have been demanded due to the miniaturization and higher output of electronic devices, lasers, and energy harvesting/storage systems. Graphene nanosheet suspension has attracted attention as a next-generation nanofluid because of its high thermal conductivity and low pressure drop, while being dispersed stably without any additives. Graphene-based nanofluids have been mostly investigated using graphene oxide, and there are a few studies on pure graphene because of the limitation in mass production and stabilization at high concentrations of graphene. In this study, we prepared a 10 wt. % high-concentration few-layer graphene suspension by pulverizing graphite particles. Scanning electron microscopy, atomic force microscopy, and Raman spectra confirmed the few-layer graphene is formed in the suspension. The thermal conductivity of the suspension increased with concentration and suddenly jumped at a specific concentration. Furthermore, a significant improvement in thermal conductivity of &gt;40% compared to base liquid was confirmed at 10 wt. % graphene content. A similar trend was observed for electrical resistance; 10 wt. % graphene suspension showed 62% lower resistance than that of 1 wt. %. These results suggest the percolation of graphene in a liquid, which has not been observed for graphene-based materials in previous research.

DOI： 10.1063/5.0210446

Size, polyglycerol grafting, and net surface charge of iron oxide nanoparticles determine their interaction and toxicity in Caenorhabditis elegans. Reviewed International journal

Yajuan Zou, Yutaka Shikano, Yuta Nishina, Naoki Komatsu, Eriko Kage-Nakadai, Masazumi Fujiwara

Chemosphere 358 142060 - 142060 2024.4

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

The widespread application of engineered nanoparticles (NPs) in environmental remediation has raised public concerns about their toxicity to aquatic organisms. Although appropriate surface modification can mitigate the ecotoxicity of NPs, the lack of polymer coating to inhibit toxicity completely and the insufficient knowledge about charge effect hinder the development of safe nanomaterials. Herein, we explored the potential of polyglycerol (PG) functionalization in alleviating the environmental risks of NPs. Iron oxide NPs (ION) of 20, 100, and 200 nm sizes (IONS, IONM and IONL, respectively) were grafted with PG to afford ION-PG. We examined the interaction of ION and ION-PG with Caenorhabditis elegans (C. elegans) and found that PG suppressed non-specific interaction of ION with C. elegans to reduce their accumulation and to inhibit their translocation. Particularly, IONS-PG was completely excluded from worms of all developmental stages. By covalently introducing sulfate, carboxyl and amino groups onto IONS-PG, we further demonstrated that positively charged IONS-PG-NH3+ induced high intestinal accumulation, cuticle adhesion and distal translocation, whereas the negatively charged IONS-PG-OSO3- and IONS-PG-COO- were excreted out. Consequently, no apparent deleterious effects on brood size and life span were observed in worms treated by IONS-PG and IONS-PG bearing negatively charged groups. This study presents new surface functionalization approaches for developing ecofriendly nanomaterials.

DOI： 10.1016/j.chemosphere.2024.142060

Synergistic Functionalization of Graphene Oxide: Electrochemical Devices and Ritter Catalysis

Muhammad Sohail Ahmad, Yuta Nishina, Yusuke Inomata, Andri Haridiansyah, Tetsuya Kida

Journal of Physical Chemistry C 128 ( 14 ) 5860 - 5866 2024.4

Publishing type：Research paper (scientific journal)

Graphene oxide (GO) is a versatile platform with unique properties that find broad applications in electronics and catalysis. The double covalent functionalization of GO under mild conditions offers an efficient approach to fine-tune its properties. Herein, we present an approach involving the ring-opening reaction of epoxide groups of the GO by amines, followed by subsequent covalent linking of the sulfonated functionalized polymer. Characterization of the functionalized GO via various techniques confirms the successful surface functionalization with diverse functional groups. The mild condition employed preserves the structure and properties of GO, which demonstrates that GO can be tailored for specific applications, such as a platform for electrochemical devices and a solid acid catalyst for the Ritter reaction.

DOI： 10.1021/acs.jpcc.3c07871

Effect of electrolytic conditions on the structure of exfoliated products of graphite using sulfuric acid and their ability as hydrogen production electrocatalyst supports

Ryuichi Maekawa, Hirooki Kajiwara, Yusuke Muramatsu, Takumi Hisadome, Koki Suzaki, Yasushi Nishikawa, Naoto Kuwamura, Toshinori Okura, Yuta Nishina, Hideki Hashimoto

Electrochimica Acta 479 2024.3

Publishing type：Research paper (scientific journal)

Anodic electrochemical exfoliation of graphite in a simple two-electrode configuration using inexpensive and industrially available sulfuric acid is an excellent process for the mass production of graphene oxide. In this study, the effects of the structure of the graphite sheet, voltage and current, and electrolyte concentration on the structure of the exfoliated products and their potential use as a catalyst support were investigated. The results showed that graphite structure is a factor affecting the uniformity of the electrolytic reaction, that voltage/current is an important factor that can determine whether expansion or exfoliation of the graphite anode is preferentially caused, and that electrolyte concentration is an important factor determining the atomistic structure of the exfoliated products. In addition, they showed excellent ability as catalyst supports for a molecular metal complex showing heterogeneous electrocatalytic hydrogen production. Of note is that the catalytic currents are dependent on the structure such as size, defects, and oxidation degree of exfoliated products.

DOI： 10.1016/j.electacta.2024.143893

Surface Modifications of Medical Grade Stainless Steel

Nusrat Sultana, Yuta Nishina, Mohammed Zahedul Islam Nizami

Coatings 2024.2

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