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Tag: Tohoku University

  • Novel Catalyst Model Sets New Standards in Fuel Cell Technology

    Novel Catalyst Model Sets New Standards in Fuel Cell Technology

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    Chemistry Catalyst Concept

    Researchers at Tohoku University have developed a novel method to predict the performance of molecular metal-nitrogen-carbon (M-N-C) catalysts, which are essential for the advancement of fuel cell technology. Their study highlights a new predictive tool that relies on computer simulations to study the interactions between electric fields and pH levels. This breakthrough provides a more efficient pathway for developing catalysts that operate effectively in different environmental conditions, potentially overcoming one of the major hurdles in the widespread adoption of fuel cell technology.

    Tohoku University researchers have devised a method to predict the performance of new catalysts for fuel cells, potentially hastening the development of more efficient clean energy solutions.

    Tohoku University researchers have created a reliable means of predicting the performance of a new and promising type of catalyst. Their breakthrough will speed up the development of efficient catalysts for both alkaline and acidic environments, thereby saving time and effort in future endeavors to create better fuel cells.

    Details of their research were recently published in the journal Chemical Science.

    Structures of Long Chain Fe Azaphthalocyanines Molecular Catalysts

    Structures of long-chain Fe-Azaphthalocyanines (AzPc) molecular catalysts. After DFT geometric relaxations with more than 650 atoms, different “dancing patterns” emerged due to the varying interactions between the molecular side chains and the graphene substrate. Credit: Hao Li, Hiroshi Yabu et al.

    Fuel cell technology has often been touted as a promising solution for clean energy; however, issues with catalyst efficiency have impeded its broad adoption.

    Molecular metal-nitrogen-carbon (M-N-C) catalysts boast distinctive structural properties and excellent electrocatalytic performance, particularly for the oxygen reduction reaction (ORR) in fuel cells. They offer a cost-effective alternative to platinum-based catalysts.

    Unique Properties of M-N-C Catalysts

    One such variant of M-N-C catalysts are metal-doped azaphthalocyanine (AzPc). These possess unique structural properties, characterized by long stretching functional groups. When these catalysts are placed on a carbon substrate, they take on three-dimensional shapes, much like a dancer placed onto a stage. This shape change influences how well they work for ORR at different pH levels.

    Experimental RDE Polarization Curves

    Experimental RDE polarization curves are provided at pH = 1 and pH = 13. This figure offers direct comparisons between the experimental and simulated half-wave potentials. Credit: Hao Li, Hiroshi Yabu et al.

    Still, translating these beneficial structural properties into increased performances is a challenge, one that requires significant modeling, validation, and experimentation, which is resource intensive.

    “To overcome this, we used computer simulations to study how the performance of carbon-supported Fe-AzPcs catalyst for oxygen reduction reactions changes with different pH levels, by looking at how electric fields interact with the pH and the surrounding functional group,” says Hao Li, associate professor at Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR) and corresponding author of the paper.

    pH Dependent ORR Volcano Models and the Simulated LSV Curves of Fe AzPc Derivatives

    pH-dependent ORR volcano models and the simulated LSV curves of Fe-AzPc derivatives. pH-field dependent volcanos. The left and right sides of the color bar represent the correlation between the electric field and pH. This figure serves as a benchmark for our experiments. Credit: Hao Li, Hiroshi Yabu et al.

    In analyzing Fe-AzPcs performance in ORR, Li and his colleagues incorporated large molecular structures with complex long-chain arrangements, or ‘dancing patterns,’ with arrangements of over 650 atoms.

    Crucially, the experimental data revealed that the pH-field coupled microkinetic modeling closely matched the observed ORR efficiency.

    “Our findings suggest that evaluating the charge transfer occurring at the Fe-site, where the Fe atom usually loses approximately 1.3 electrons, could serve as a useful method for identifying suitable surrounding functional groups for ORR,” adds Li. “We have essentially created a direct benchmark analysis for the microkinetic model to identify effective M-N-C catalysts for ORR across various pH conditions.”

    Reference: “Benchmarking pH-field coupled microkinetic modeling against oxygen reduction in large-scale Fe–azaphthalocyanine catalysts” by Di Zhang, Yutaro Hirai, Koki Nakamura, Koju Ito, Yasutaka Matsuo, Kosuke Ishibashi, Yusuke Hashimoto, Hiroshi Yabu and Hao Li, 15 March 2024, Chemical Science.
    DOI: 10.1039/D4SC00473F



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  • New Research Links Structure to Reaction Performance

    New Research Links Structure to Reaction Performance

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    Chemistry Catalyst Concept

    A team of researchers has developed a new research paradigm which simplifies the understanding of how catalyst structures affect their reactions. The study focused on the electrochemical CO2 reduction reaction using Tin-Oxide-based catalysts, revealing crucial insights into the active surface species and their performance. This breakthrough allows for the tailored design of efficient catalysts and paves the way for further exploration of electrocatalytic reactions, aiming to enhance the development of scalable and high-performance electrocatalysts.

    In a significant advance in the fight against climate change and the shift towards sustainability, a team of researchers has introduced a new research framework that simplifies understanding how catalyst structures influence their reactions.

    Details of the researchers’ breakthrough were published in the journal Angewandte Chemie.

    Understanding how a catalyst’s surface affects its activity can aid the design of efficient catalyst structures for specific reactivity requirements. However, grasping the mechanisms behind this relationship is no straightforward task given the complicated interface microenvironment of electrocatalysts.

    “To decipher this, we honed in on the electrochemical CO2 reduction reaction (CO2RR) in Tin-Oxide-based (Sn-O) catalysts,” points out Hao Li, associate professor at Tohoku University’s Advanced Institute for Materials Research (WPI-AIMR) and corresponding author of the paper. “In doing so, we not only uncovered the active surface species of SnO2-based catalysts during CO2RR but also established a clear correlation between surface speciation and CO2RR performance.”

    Structure Property Activity Relationships for the Electrochemical CO2 Reduction Reaction Over SnO2

    The standard research paradigm uncovers the structure-property-activity relationships for the electrochemical CO2 reduction reaction (CO2RR) over SnO2. This picture illustrates the surface reconstruction induced by oxygen vacancies (1/1 ML coverage) and surface-active species (Sn layer) accountable for selective HCOOH production. Credit: Hao Li et al.

    Promising Method for CO2 Reduction

    CO2RR is recognized as a promising method for reducing CO2 emissions and producing high-value fuels, with formic acid (HCOOH) being a noteworthy product because of its various applications in industries such as pharmaceuticals, metallurgy, and environmental remediation.

    The proposed method helped identify the genuine surface states of SnO2 responsible for its performance in CO2 reduction reactions under specific electrocatalytic conditions. Moreover, the team corroborated their findings through experiments using various SnO2 shapes and advanced characterization techniques.

    Li and his colleagues developed their methodology by combining theoretical studies with experimental electrochemical techniques.

    “We bridged the gap between the theoretical and experimental, offering a comprehensive understanding of catalyst behavior under real-world conditions in the process,” adds Li.

    The research team is now focused on applying this methodology to a variety of electrochemical reactions. In doing those, they hope to uncover more about unique structure-activity correlations, accelerating the design of high-performance and scalable electrocatalysts.

    Reference: “Deciphering Structure-Activity Relationship Towards CO2 Electroreduction over SnO2 by A Standard Research Paradigm” by Zhongyuan Guo, Yihong Yu, Congcong Li, Egon Campos dos Santos, Tianyi Wang, Huihui Li, Jiang Xu, Chuangwei Liu and Hao Li, 29 January 2024, Angewandte Chemie International Edition.
    DOI: 10.1002/anie.202319913



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  • Japanese Scientists Unveil Game-Changing Material for Magnesium Batteries

    Japanese Scientists Unveil Game-Changing Material for Magnesium Batteries

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    Battery Technology Illustration

    Researchers at Tohoku University have developed a new cathode material for rechargeable magnesium batteries, enabling efficient charging and discharging at low temperatures. This breakthrough, utilizing an enhanced rock-salt structure and a high-entropy strategy, overcomes previous challenges in magnesium diffusion and transport.

    Scientists at Tohoku University have achieved a significant breakthrough in battery technology by creating a new cathode material for rechargeable magnesium batteries (RMBs). This material facilitates efficient charging and discharging processes, even in cold environments. By utilizing an improved rock-salt structure, this pioneering material is set to revolutionize energy storage options, making them more cost-effective, safer, and higher in capacity.

    Details of the findings were published in the Journal of Materials Chemistry A on March 15, 2024.

    The study showcases a considerable improvement in magnesium (Mg) diffusion within a rock-salt structure, a critical advancement since the denseness of atoms in this configuration had previously impeded Mg migration. By introducing a strategic mixture of seven different metallic elements, the research team created a crystal structure abundant in stable cation vacancies, facilitating easier Mg insertion and extraction.

    This represents the first utilization of rocksalt oxide as a cathode material for RMBs. The high-entropy strategy employed by the researchers allowed the cation defects to activate the rocksalt oxide cathode.

    Overcoming RMB Limitations

    The development also addresses a key limitation of RMBs – the difficulty of Mg transport within solid materials. Until now, high temperatures were necessary to enhance Mg mobility in conventional cathode materials, such as those with a spinel structure. However, the material unveiled by Tohoku University researchers operates efficiently at just 90°C, demonstrating a significant reduction in the required operating temperature.

    Game Changing Material for Magnesium Batteries Graphic

    The present material contains many metal elements as cations thanks to the effect of the high configurational entropy. Credit: Tohoku University

    Tomoya Kawaguchi, a professor at Tohoku University’s Institute for Materials Research (IMR), notes the broader implications of the study. “Lithium is scarce and unevenly distributed, whereas magnesium is abundantly available, offering a more sustainable and cost-effective alternative for lithium-ion batteries. Magnesium batteries, featuring the newly developed cathode material, are poised to play a pivotal role in various applications, including grid storage, electric vehicles, and portable electronic devices, contributing to the global shift towards renewable energy and reduced carbon footprints.”

    Kawaguchi collaborated with Tetsu Ichitsubo, also a professor at IMR, who states, “By harnessing the intrinsic benefits of magnesium and overcoming previous material limitations, this research paves the way for the next generation of batteries, promising significant impacts on technology, the environment, and society.”

    Ultimately, the breakthrough is a major step forward in the quest for efficient, eco-friendly energy storage solutions.

    Reference: “Securing cation vacancies to enable reversible Mg insertion/extraction in rocksalt oxides” by Tomoya Kawaguchi, Masaya Yasuda, Natsumi Nemoto, Kohei Shimokawa, Hongyi Li, Norihiko L. Okamoto and Tetsu Ichitsubo, 15 March 2024, Journal of Materials Chemistry A.
    DOI: 10.1039/D3TA07942B



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