Language：English   Publisher：Journal of Physical Chemistry C  

The development of high-performance Pt-based electrocatalysts with reduced metal loading is crucial for advancing proton exchange membrane fuel cell technology. Herein, we present a dual structure-directing agent approach for the precise formation of superstructures in uniform PtCoCu ternary alloy nanoparticles. Using zinc phthalocyanine for coordination-based composition control and dicyandiamide for carbon-mediated sintering suppression enabled molecular-level mixing and formation of an L1<inf>0</inf> face-centered cubic superstructure with exceptional uniformity and controlled electronic properties. The optimized L1<inf>0</inf>-Pt<inf>45</inf>Co<inf>24</inf>Cu<inf>31</inf> electrocatalyst exhibited remarkable oxygen reduction reaction activity with a mass activity of 2.13 A/mg<inf>Pt</inf> at 0.9 V vs the reversible hydrogen electrode, representing a 7-fold improvement over commercial Pt/C and exceeding the DOE 2025 target by 483%. The electrocatalyst also demonstrated excellent durability, retaining more than 70% of its initial mass activity after 30 000 potential cycles. Comprehensive density functional theory calculations revealed that ternary alloying optimized the Pt and overall d-band centers, which were located at −2.87 and −2.50 eV, respectively, clarifying the electronic origin of the enhanced electrocatalytic performance. This dual structure-directing strategy overcomes the conventional trade-off between ordered phase formation and particle size control, demonstrating the potential of a tailored precursor design for developing next-generation electrocatalysts with precisely controlled superstructures.

DOI： 10.1021/acs.jpcc.5c06519

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Scopus

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

DOI： 10.1016/j.jelechem.2025.119370

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Scopus

Language：English   Publisher：Journal of Electroanalytical Chemistry  

The oxygen reduction reaction (ORR) remains a performance-limiting step in fuel cells due to sluggish kinetics and the high cost of platinum-based catalysts. In this study, we report the synthesis of nitrogen and phosphorus co-doped carbon (NPC) encapsulating Pt nanoparticles via a solution plasma process, aiming to reduce Pt usage while enhancing catalyst activity and durability. Structural characterization confirmed a core–shell morphology, with Pt cores uniformly embedded in a conductive, heteroatom-doped carbon shell. X-ray photoelectron spectroscopy revealed active nitrogen species (pyridinic and graphitic N) and P-doping contributing to electron redistribution and active site formation. Electrochemical tests in alkaline media demonstrated that the resulting NPC@Pt catalyst exhibits superior ORR activity, with a four-electron transfer pathway, higher limiting current density, and significantly improved long-term stability compared to commercial Pt/C. These findings highlight the synergy of heteroatom doping and core–shell structuring in advancing cost-effective, durable ORR electrocatalysts for alkaline fuel cells.

DOI： 10.1016/j.jelechem.2025.119273

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Microbiology, Molecular and Cellular Biosciences Research Foundation  

<p>The extracellular export of target chemicals is essential for achieving the target productivity of microbial cell factories (MCFs). We demonstrated that MscCG, a mechanosensitive channel responsible for glutamate export in glutamate-producing MCF of <i>Corynebaterium glutamicum</i>, can export various intracellular low-molecular-weight chemicals outside the cell. The mechanosensitive channels exporter improved L-Lys productivity and conferred substantial 5′-IMP fermentative production ability to the <i>Escherichia coli</i> MCF, which lacks inherent 5′-IMP exporters, indicating that mechanosensitive channels, which are low selective, functioned effectively as MCF exporters. We also demonstrated the effectiveness of a gain-of-function (GOF) mutation of mechanosensitive channels as MCF exporters; however, the essential mechanism underlying this GOF mutation remains unknown. Therefore, we performed molecular dynamics simulations to identify this mechanism at the atomic level. Consequently, we partially elucidated the underlying mechanism of G46D-induced GOF in MscL, which was effective as a 5′-IMP exporter. Specifically, the kink at A38 in the inner transmembrane helix of MscL forming its pore can affect GOF behavior. Based on these results, we conclude that mechanosensitive channels have potential as innovative and versatile exporters of MCFs, capable of enhancing the production efficiency of target chemicals and enabling their production in the absence of natural exporters.</p>

DOI： 10.2323/jgam.2025.09.002

Open Access

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PubMed

CiNii Research

Language：English   Publisher：ACS Sustainable Chemistry and Engineering  

The conventional recycling of Zn–C batteries typically relies on either the disposal into landfills or the direct incineration, yielding adverse pollution and unnecessary carbon emissions to the environment and atmosphere. Even though one of the main components in the batteries, the carbon rod could serve as a valuable secondary carbon source. Herein, we present a sustainable method to recycle waste Zn–C battery graphite as high-performance lithium-ion battery (LiBs) anodes through thermal and alkaline (KOH) treatments. Extensive structural and surface analyses revealed that the optimized treatment (RG H–K) removed metal impurities and beneficial surface activation through defect generation and functional group stabilization. This facilitated lithium-ion transport kinetics along the activated surface architecture and stabilized solid–electrolyte interphase (SEI) formation. Electrochemical measurements showed excellent performance in which the specific capacity of RG H–K achieved 364.51 mAh/g at 0.2C and 255.88 mAh/g at 5C, along with stable long-term cycling (&gt;200 cycles) at 1C, maintaining a capacity of ∼350 mAh/g. These findings highlight the potential of engineered surface modification in upcycling waste graphite into high-performance, environmentally sustainable LIB anodes.

DOI： 10.1021/acssuschemeng.5c04658

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Language：English   Publisher：Journal of Physical Chemistry C  

In this study, we aimed to synthesize a ternary PtPdCu nanoalloy catalyst supported on commercially available carbon black. A one-step solvothermal method with the addition of urea was adopted to obtain alloy nanoparticles of uniform size. Results showed that the adsorption and desorption of oxygen intermediates were improved in Pt<inf>48</inf>Pd<inf>32</inf>Cu<inf>20</inf> nanoparticles, and the overpotential was greatly reduced. In addition, the RDE test demonstrated a mass activity of 917 mA mg-1 Pt + Pd, which is approximately five times higher than the mass activity of commercial Pt/C (197 mA mg-1 Pt). Furthermore, the accelerated stress test showed that PtPdCu exhibited superior stability compared with commercial Pt/C. In the H<inf>2</inf>-O<inf>2</inf> fuel cell, the maximum power output was 887 mW cm^-2, with low Pt and Pd loading (13 wt % PtPd/C) on the cathode. X-ray photoelectron spectroscopy (XPS) analysis revealed that the introduction of Pd causes the center of the Pt valence band to shift to an appropriate position, thereby weakening the adsorption of oxygen-containing intermediates throughout the PtPdCu alloy and improving the catalytic performance.

DOI： 10.1021/acs.jpcc.5c01985

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Language：English   Publisher：Rsc Advances  

Platinum-based catalysts are widely used in polymer electrolyte fuel cells (PEMFCs) due to their excellent catalytic activity for the oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR). In this study, a PtPdIr ternary alloy catalyst was synthesized by a solution plasma (SP) sputtering process with PtPd and PtIr erelctrodes, which provides a non-equilibrium reaction field in solution. The ratio of Ir in the PtPdIr nanoparticles increased as the ratio of Ir in the PtIr electrode increased. However, the ratio reamined constant at about 10%. The size of the nanoparticles could be controlled in the range of 1-3 nm. In addition, the nanoparticles were well dispersed when supported on carbon and no agglomeration was observed. The electrochemical properties of the obtained nanoparticles were investigated in terms of ORR and HOR, and the particle-c (79 : 14 : 7) nanoparticle exhibited the highest ORR and HOR performance. XPS analysis showed that the intensity of I<inf>Pd(ii)</inf> and I<inf>Pd(0)</inf> in particle-c (79 : 14 : 7) was at the same level, and that the chemical bonding state of these elements enhances ORR and HOR activity.

DOI： 10.1039/d5ra01747e

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PubMed

Language：English   Publisher：Nanoscale Advances  

Fuel cells have become increasingly important in recent years because of their high energy efficiency and low environmental impact. However, key challenges remain in the widespread adoption of fuel-cell vehicles, including reducing Pt usage in catalysts and improving their durability. In this study, a high-performance Pt@carbon-dot-film core–shell catalyst was successfully synthesized using a nonequilibrium reaction field, i.e., solution plasma (SP) process, by adjusting the electrolyte pH. Four pH solutions (pH = 4.4, 7, 8, and 11) were employed as the discharge liquid environment for the SP process. The catalyst synthesized in the pH = 8 solution exhibited a mass activity of approximately 500 mA mg⁻¹, which was twice as high as that of the commercial Pt/C catalyst (256 mA mg⁻¹) with the same loading amount. The onset and half-wave potentials were 0.99 and 0.89 V, respectively, both of which exceeded those of commercial Pt/C catalysts (0.95 and 0.86 V, respectively). Furthermore, the enhanced catalytic performance corresponded to the Pt/C bonding between Pt and the carbon shell generated during the SP process.

DOI： 10.1039/d4na00818a

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PubMed

Language：English   Publisher：Coatings  

In this study, the growth of 2D MoS<inf>2</inf> thin films on SiO<inf>2</inf>/Si substrates was investigated using sodium dodecyl sulfate (SDS) micellar solutions, and the effects of SDS concentration and substrate treatment on crystal growth were evaluated. By increasing the SDS concentration, the wettability was improved, and uniform MoS<inf>2</inf> crystal growth was promoted by micellar formation. When the SDS concentration exceeded 10⁻⁴ mol/L, the static contact angle sharply decreased, indicating uniform 2D material growth. The optimal conditions that enabled a uniform supply of Mo-based precursors were as follows: SDS concentration of 3.5 × 10⁻⁴ mol/L; Na<inf>2</inf>MoO<inf>4</inf>·2H<inf>2</inf>O concentration of 1.7 × 10⁻² mol/L. The results indicate that solution-based processes using SDS are effective for 2D material growth, and they may be a valuable technique in future thin film device fabrication processes.

DOI： 10.3390/coatings15010004

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Publishing type：Research paper (scientific journal)  

This study aimed to synthesize few-layer MoS2 on SiO2/Si using sulfurization chemical vapor deposition toward beyond-5G and 6G communication. Fabric-like MoO3(s) was directly placed onto a SiO2/Si substrate to lower the oxygen potential, which is achieved through a shadowing effect on vaporization. Successful results were achieved, yielding MoS2 thin films with a coverage of more than 74% and a crystal size in the range of 50 to 600 μm. Two distinct pathways for MoS2(s) formation from MoO3(s) via MoO2(s) and MoS3(s) were also uncovered. The shadowing effect of MoO3(s) vaporization facilitated the two-dimensional growth of MoS2 by mitigating oxygen partial pressure. Therefore, sulfurization chemical vapor deposition shows great application potential in synthesizing high-quality MoS2 thin films with substantial crystal size and coverage, making them suitable for next-generation communication devices.

DOI： 10.1021/acsanm.4c03188

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Scopus

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

With the goal of developing lightweight Al-Ti-containing multicomponent alloys with excellent mechanical strength, an Al–Ti–Cu–Co alloy with a phase-separated microstructure was prepared. The granulometry of metal particles was reduced using planetary ball milling. The particle size of the metal powders decreased as the ball milling time increased from 5, 7, to 15 h (i.e., 6.6 ± 6.4, 5.1 ± 4.3, and 3.2 ± 2.1 μm, respectively). The reduction in particle size and the dispersion of metal powders promoted enhanced diffusion during the spark plasma sintering process. This led to the micro-phase separation of the (Cu, Co)2AlTi (L21) phase, and the formation of a Cu-rich phase with embedded nanoscale Ti-rich (B2) precipitates. The Al–Ti–Cu–Co alloys prepared using powder metallurgy through the spark plasma sintering exhibited different hardnesses of 684, 710, and 791 HV, respectively, while maintaining a relatively low density of 5.8–5.9 g/cm3 (<6 g/cm3). The mechanical properties were improved due to a decrease in particle size achieved through increased ball milling time, leading to a finer grain size. The L21 phase, consisting of (Cu, Co)2AlTi, is the site of basic hardness performance, and the Cu-rich phase is the mechanical buffer layer between the L21 and B2 phases. The finer network structure of the Cu-rich phase also suppresses brittle fracture.

DOI： 10.3390/ma17020304

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PubMed

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

An attention to a Li ion battery for electric vehicles has been attracted, but there are two huge problems: a short mileage and slow charging speed. Therefore, it is required to improve the specific capacity and electrical conductivity of the carbon material used for an anode and a conductive agent. To solve these problems, this study organized correlation analysis with descriptor vectors by collecting experimental properties including capacity and conductivity from 21 various types of carbon materials. Focusing on the flux of Li ion, it was found that the capacity was dependent on the intercalation of Li ions, which lead to propose the correlation equation based on the Hill equation. Furthermore, the intercalation occurred at the edge of basal plane lead an increase of the width of the gap between two graphene layers, followed by a diffusion through the basal plane, finally the expanded gap recovered its original width. Also, it was found that the variables which are sensitive to the conductivity are largely dependent on the defects and especially the number of graphene layers around the surface, which proposed a correlation equation that can predict the capacity and conductivity. To validate these functions, we checked the effectiveness of it with both experimental data from 27 previous studies and statistical method. As a result, it was confirmed enough to predict them. Finally, a candidate structure for improving the battery performance was proposed, thus our study aims to guide the exploration of electrode materials for LIBs.

DOI： 10.1016/j.carbon.2023.118479

Open Access

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Scopus

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

Though expensive platinum (Pt) is used as catalyst for oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs), insufficient durability remains as a bottleneck for commercialization of PEFCs. Improving both catalytic performance and durability by graphene encapsulation is an attractive strategy to solve this problem. In this study, graphene-encapsulated PtFe core-shell catalyst is synthesized with dimethyl formamide (DMF) and a pair of Pt and Fe electrodes without using any metal salts by utilizing the solution plasma (SP) process. TEM and EELS results show synthesized PtFe nanoparticles are encapsulated with close to single-layered highly crystallized graphene. Although commercial Pt/C showed significant performance degradation (ECSA −33%, MA −68%) after 50,000 cycles of accelerated durability test (ADT), PtFe core-shell catalyst shows remarkably improved durability (ECSA −13%, MA −19%) while graphene shell clearly remains. The improved durability is more prominent in the single cell test, the decrease in maximum power density after 6000 cycles of ADT was significantly lower as −1.2%, compared to that of Pt/C (−52.1%). This study introduces a novel and attractive catalyst synthesis process by the SP method followed by heat treatments and suggests graphene encapsulation can improve long-term durability of catalyst while maintaining ORR activity.

DOI： 10.1016/j.jpowsour.2023.233419

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Scopus

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

The ternary Mg–Al–Ti and quaternary Mg–Al–Ti–Cu systems were prepared by mechanical alloying in oxygen-lean atmosphere followed by spark plasma sintering. The ternary Mg–Al–Ti and quaternary Mg–Al–Ti–Cu systems which were sintered at 750 °C after 16 h milling showed the highest hardness of 509 and 947 HV with low densities of 2.9 and 3.9 g/cm3, respectively. The decrease in particle size and uniform dispersion of elements through optimization of the MA process induced the formation of uniform composite microstructure after SPS. Moreover, the addition of the fourth element, Cu, showed a significant impact on the improvement in hardness. This result was explained from the perspective of the microstructure and the electronic nature of elements. Our results provide a facile method for synthesizing oxide/metal composites from elemental powders without a separate oxidation process. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1557/s43578-023-01137-z

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Scopus

Language：English  

Publishing type：Research paper (scientific journal)   Publisher：LIDSEN Publishing Inc  

Crystalline lithium fluoride (LiF) has been intensively pursued as potential alternative solid electrolytes (SEs) owing to its excellent chemical and electrochemical oxidation stability, and good deformability. However, due to its low ion conductivity, LiF is still challenging for practical SE applications. Herein, Li-Zr-F composite-based SE by liquid-mediated synthesis is proposed to be studied. methanol (CH&lt;sub&gt;3&lt;/sub&gt;OH) was mainly evaluated as a liquid-mediated precursor for synthesizing Li-Zr-F composites under the stoichiometric proportion of LiF and ZrF4 (2:1 and 2:0.8) and a subsequent annealing process at 25°C/150°C, 50°C/150°C, and 70°C/150°C, respectively. X-ray diffraction results revealed that the Li-Zr-F composites could be crystallized in the three main types of phase formations, including Li&lt;sub&gt;2&lt;/sub&gt;ZrF&lt;sub&gt;6&lt;/sub&gt; ( ), Li&lt;sub&gt;2&lt;/sub&gt;ZrF&lt;sub&gt;6&lt;/sub&gt; ( ), and Li&lt;sub&gt;4&lt;/sub&gt;ZrF&lt;sub&gt;8&lt;/sub&gt; ( ) octahedron structures. In addition, the effect of cation stack sublattice synthesized by methanol mediator on the ion conduction of Li-Zr-F composites was investigated by using electrochemical impedance spectroscopy (EIS). Through the Zr&lt;sup&gt;4+&lt;/sup&gt;-substitution, Li&lt;sub&gt;2&lt;/sub&gt;ZrF&lt;sub&gt;6&lt;/sub&gt; ( )-based SE exhibited the highest ion conduction which was increased to 2.40 × 10&lt;sup&gt;-8&lt;/sup&gt; S/cm and 3.89 × 10&lt;sup&gt;-8&lt;/sup&gt; S/cm under the stoichiometric proportion of LiF and ZrF&lt;sub&gt;4&lt;/sub&gt; 2:0.8 at a dried temperature of 50°C/150°C with, respectively. A 0.21 eV activation energy ( ) was achieved for a battery with Li&lt;sub&gt;2&lt;/sub&gt;ZrF&lt;sub&gt;6&lt;/sub&gt; ( )-based SE. Meanwhile, LiF exhibited up to 0.78 eV leading to a low kinetic rate for ion diffusion. These results implied that Li&lt;sub&gt;2&lt;/sub&gt;ZrF&lt;sub&gt;6 &lt;/sub&gt;( )-based SE was successfully synthesized under the optimal condition of CH&lt;sub&gt;3&lt;/sub&gt;OH-50°C/150°C which could improve the ion-conductivity of LiF.

DOI： 10.21926/jept.2301010

Publishing type：Research paper (scientific journal)  

A high-rate oxygen reduction reaction (ORR) is necessary for polymer electrolyte membrane fuel cells (PEMFC). In this work, by using a solution plasma technique, Pt catalytic particles coated with N-doped graphene (Pt-NG) were effectively produced at 25°C. According to transmission electron microscope images, the average diameter of Pt particles was 4 nm, while the graphene layer thickness was less than 1 nm. A catalytic layer of Pt-NG supported on single-walled carbon nanotubes (Pt-NG/SWCNT) was synthesized. Cyclic voltammetry was used to assess the ORR characteristics of Pt-NG/SWCNT catalytic layers. Only at a density of SWCNT to solvent ratio of 0.75 mg ml−1 were the ORR peaks clearly visible. Because of the high resistivity of SWCNT layers, the ORR peaks in other ranges, 0.4 mg ml−1 to 2.0 mg ml−1, were not clearly observed. The effect of SWCNT concentration on conductivity was proven to follow the basic concept of the percolation threshold.

DOI： 10.1002/fuce.202200020

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Scopus

Publishing type：Research paper (scientific journal)  

The solution plasma process (SPP) can provide a low-temperature reaction field, leading to an effective synthesis of N-doped graphene with a high N content and well-structured planar structure. However, the interactions at the plasma–solution interface have not been well understood; therefore, it needs to be urgently explored to achieve the modulation of the SPP. Here, to address the knowledge gap, we experimentally determined the physical parameters of the spital distribution in the plasma phase, plasma–gas phase, and gas–liquid phase of the SPP by the Langmuir probe system with modification. Based on the assumption that plasma can act similarly to semiconductors with the Fermi level above the vacuum level, an energy band diagram of the plasma–solution junction could be proposed for the first time. It was observed that the Fermi level of the organic molecule could determine the magnitude of electron temperature in plasma, i.e., benzene produced the highest electron temperature, followed by phenol, toluene, and aniline. Finally, we found that the electron temperature at the interface could induce quenching, leading to the formation of multilayer large-size-domain carbon products. It provided significant evidence for achieving nonequilibrium plasma modulation of carbon nanomaterial synthesis.

DOI： 10.3390/coatings12111607

Open Access

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Scopus

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：Japanese  

DOI： 10.1016/j.bpj.2017.11.642

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Authorship：Lead author   Language：English   Publishing type：Research paper (conference, symposium, etc.)  

DOI： 10.1016/j.bpj.2016.11.2882

Web of Science

Authorship：Lead author   Language：Japanese  

DOI： 10.20585/cryobolcryotechnol.57.1_19

Open Access

Language：Japanese  

Language：Japanese