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Journal Articles

Electrochemically driven specific alkaline metal cation adsorption on a graphene interface

Yasuda, Satoshi; Tamura, Kazuhisa; Kato, Masaru*; Asaoka, Hidehito; Yagi, Ichizo*

Journal of Physical Chemistry C, 125(40), p.22154 - 22162, 2021/10

https://doi.org/10.1021/acs.jpcc.1c03322

Understanding electrochemical behavior of the alkaline metal cation-graphene interface in electrolyte is essential for understanding the fundamental electrochemical interface and development of graphene-based technologies. We report comprehensive analysis of the electrochemical behavior of both alkaline metal cations and graphene using electrochemical surface X-ray diffraction (EC-SXRD) and Raman (EC-Raman) spectroscopic techniques in which the interfacial structure of cations and the charging state and mechanical strain of the graphene can be elucidated. EC-SXRD and cyclic voltammetry demonstrated electrochemically driven specific adsorption and desorption of cations on the graphene surface involved in the dehydration and hydration process. This study provides new insight for understanding fundamental electrochemical behavior of the alkaline metal cation-graphene interface and contributes to the development of carbon-based novel applications.

Journal Articles

Synchrotron radiation-based techniques available at JAEA advanced characterization nanotechnology platform (Japan Atomic Energy Agency)

Yoneda, Yasuhiro; Yoshigoe, Akitaka; Takeda, Yukiharu; Shiwaku, Hideaki; Matsumura, Daiju; Shobu, Takahisa; Tamura, Kazuhisa

Materia, 58(12), p.763 - 769, 2019/12

https://doi.org/10.2320/materia.58.763

This is an introduction to the equipment provided for each implementation period belonging to the structure analysis platform in the nanotechnology platform.

Journal Articles

Controlled deuterium labelling of imidazolium ionic liquids to probe the fine structure of the electrical double layer using neutron reflectometry

Akutsu, Kazuhiro*; Cagnes, M.*; Tamura, Kazuhisa; Kanaya, Toshiji*; Darwish, T. A.*

Physical Chemistry Chemical Physics, 21(32), p.17512 - 17516, 2019/08

https://doi.org/10.1039/C9CP02479D

Times Cited Count：3 Percentile：32.79(Chemistry, Physical)

We combined the deuterium labeling and neutron reflectivity techniques to determine the fine structure of the electric double layer structure in an imidazolium ionic liquid (IL). For this, a simple and large scale deuteration method for imidazolium ILs was developed, where the deuteration level can be systematically controlled.

Journal Articles

Structure of active sites of Fe-N-C nano-catalysts for alkaline exchange membrane fuel cells

Kishi, Hirofumi*; Sakamoto, Tomokazu*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Kato, Takeshi*; Zulevi, B.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; Matsumura, Daiju; et al.

Nanomaterials (Internet), 8(12), p.965_1 - 965_13, 2018/12

https://doi.org/10.3390/nano8120965

Times Cited Count：6 Percentile：39.54(Chemistry, Multidisciplinary)

Journal Articles

Reversible structural changes and high-rate capability of Li $_{3}$ PO $_{4}$ -modified Li $_{2}$ RuO $_{3}$ for lithium-rich layered rocksalt oxide cathodes

Taminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Kim, K.-S.*; Tamura, Kazuhisa; Kanno, Ryoji*

Journal of Physical Chemistry C, 122(29), p.16607 - 16612, 2018/07

https://doi.org/10.1021/acs.jpcc.8b04723

Times Cited Count：6 Percentile：37.83(Chemistry, Physical)

Lithium-rich layered rocksalt oxides are promising cathode materials for lithium-ion batteries. We investigate the effects of surface modification by amorphous Li $_{3}$ PO $_{4}$ on the structures and electrochemical reactions in the surface region of an epitaxial Li $_{2}$ RuO $_{3}$ (010) film electrode. Structural characterization using SXRD, HAXPES, and NR shows that surface modification by Li $_{3}$ PO $_{4}$ resulted in the partial substitution of P for Li in the surface region of Li $_{2}$ RuO $_{3}$ . The modified (010) surface exhibits better rate capability at 20 C compared to the unmodified surface. surface XRD confirmed that highly reversible structural changes occurred at the modified surface during lithium (de)intercalation. These results demonstrate that this surface modification stabilizes the crystal structure in the surface region, and it can improve the rate capability of lithium-rich layered rocksalt oxide cathodes.

Journal Articles

Electrochemical reaction mechanisms under various charge-discharge operating conditions for Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ in a lithium-ion battery

Konishi, Hiroaki*; Hirano, Tatsumi*; Takamatsu, Daiko*; Gunji, Akira*; Feng, X.*; Furutsuki, Sho*; Okumura, Takafumi*; Terada, Shohei*; Tamura, Kazuhisa

Journal of Solid State Chemistry, 262, p.294 - 300, 2018/06

https://doi.org/10.1016/j.jssc.2018.03.028

Times Cited Count：6 Percentile：51.04(Chemistry, Inorganic & Nuclear)

The potential in each state of charge (SOC) during charging of Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ is higher than that during discharging. To clarify the effect of chargedischarge operating conditions on the electrochemical reaction, Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ was charged and discharged under various charge-discharge operating ranges, and OCP, crystal structure, and oxidation states of the ransition metals were evaluated by electrochemical measurement, XRD, and XAFS. These results indicate that OCP, lattice parameters, and oxidation states of the transition metals of Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ in each SOC are not constant. The XRD results indicate that two phases, namely, LiNi $_{0.33}$ Mn $_{0.33}$ Co $_{0.33}$ O $_{2}$ -like and Li $_{2}$ MnO $_{3}$ -like, exist in Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ .

Journal Articles

Mechanisms responsible for two possible electrochemical reactions in Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ used for lithium ion batteries

Konishi, Hiroaki*; Hirano, Tatsumi*; Takamatsu, Daiko*; Gunji, Akira*; Feng, X.*; Furutsuki, Sho*; Okumura, Takafumi*; Terada, Shohei*; Tamura, Kazuhisa

Journal of Solid State Chemistry, 258, p.225 - 231, 2018/02

https://doi.org/10.1016/j.jssc.2017.10.024

Times Cited Count：7 Percentile：57.15(Chemistry, Inorganic & Nuclear)

Li $_{1.2}$ Ni $_{0.13}$ Mn $_{0.54}$ Co $_{0.13}$ O $_{2}$ is known as one of the cathode electrode material for Li ion batteries and its structure during charge and discharge process was investigated using electrochemical method and X-ray diffraction. It was found that in the charge process the structure changes in the order of Li $_{2}$ MnO $_{3}$ , LiNi $_{0.33}$ Mn $_{0.33}$ Co $_{0.33}$ O $_{2}$ , and Li $_{2}$ MnO $_{3}$ . On the other hand, in the discharge process, the structure changes in the order of Li $_{2}$ MnO $_{3}$ and LiNi $_{0.33}$ Mn $_{0.33}$ Co $_{0.33}$ O $_{2}$ .

Journal Articles

Study on the deterioration mechanism of layered rock-salt electrodes using epitaxial thin films; Li(Ni, Co, Mn)O $_{2}$ and their Zr-O surface modified electrodes

Abe, Machiko*; Iba, Hideki*; Suzuki, Kota*; Minamishima, Hiroaki*; Hirayama, Masaaki*; Tamura, Kazuhisa; Mizuki, Junichiro*; Saito, Tomohiro*; Ikuhara, Yuichi*; Kanno, Ryoji*

Journal of Power Sources, 345, p.108 - 119, 2017/03

https://doi.org/10.1016/j.jpowsour.2017.01.103

Times Cited Count：9 Percentile：44.85(Chemistry, Physical)

The surface structure of the Li(Ni, Co, Mn)O $_{2}$ electrode was studied during charge/discharge process using electrochemical methods and X-ray/Neutron scattering techniques. It was found that during charge/discharge process the coverage of spinel structure increased. The spinel structure has low electrochemical activity and is not involved in Li insertion/extraction. After the surface modification, it was found that the coverage of the spinel structure did not increase. Further, it was also found out that the Li concentration at the electrode/electrolyte interface increased.

Journal Articles

NiO/Nb $_{2}$ O $_{5}$ /C hydrazine electrooxidation catalysts for anion exchange membrane fuel cells

Sakamoto, Tomokazu*; Masuda, Teruyuki*; Yoshimoto, Koji*; Kishi, Hirofumi*; Yamaguchi, Susumu*; Matsumura, Daiju; Tamura, Kazuhisa; Hori, Akihiro*; Horiuchi, Yosuke*; Serov, A.*; et al.

Journal of the Electrochemical Society, 164(4), p.F229 - F234, 2017/01

https://doi.org/10.1149/2.0281704jes

Times Cited Count：11 Percentile：52.44(Electrochemistry)

Journal Articles

Mechanism study of hydrazine electrooxidation reaction on nickel oxide surface in alkaline electrolyte by in situ XAFS

Sakamoto, Tomokazu*; Kishi, Hirofumi*; Yamaguchi, Susumu*; Matsumura, Daiju; Tamura, Kazuhisa; Hori, Akihiro*; Horiuchi, Yosuke*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; et al.

Journal of the Electrochemical Society, 163(10), p.H951 - H957, 2016/08

https://doi.org/10.1149/2.0571610jes

Times Cited Count：21 Percentile：75.3(Electrochemistry)

Journal Articles

Study on the behavior of halide ions on the Au(111) electrode surface in ionic liquids using surface X-ray scattering

Tamura, Kazuhisa; Nishihata, Yasuo

Journal of Physical Chemistry C, 120(29), p.15691 - 15697, 2016/07

https://doi.org/10.1021/acs.jpcc.5b09704

Times Cited Count：8 Percentile：37.16(Chemistry, Physical)

The behavior of halide ions on the Au(111) electrode surface in two ionic liquids (ILs) was investigated by monitoring the structure of the electrode surface. The potential dependences of the X-ray diffraction intensity, which originate from the Au(111)-(11) structure and the surface normal structure, were measured simultaneously with cyclic voltammograms. The results revealed that halide ions are co-adsorbed with IL molecules on the electrode surface and increase the mobility of surface atoms. This suggests that the interaction between halide ions and surface Au atoms is weaker than that between IL molecules and surface Au atoms; that is, the surface properties are mainly governed by adsorbed IL molecules. Furthermore, a comparison of the two ILs revealed that the effect of halide ions on the structure of the Au(111) electrode surface depends on the strength of the interaction between IL molecules and surface Au atoms.

Journal Articles

Lithium intercalation and structural changes at the LiCoO $_{2}$ surface under high voltage battery operation

Taminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Tamura, Kazuhisa; Minato, Taketoshi*; Arai, Hajime*; Uchimoto, Yoshiharu*; Ogumi, Zempachi*; Kanno, Ryoji*

Journal of Power Sources, 307, p.599 - 603, 2016/03

https://doi.org/10.1016/j.jpowsour.2015.12.133

Times Cited Count：26 Percentile：73.4(Chemistry, Physical)

An epitaxial-film model electrode of LiCoO $_{2}$ (104) was fabricated on SrRuO $_{3}$ (100)/Nb:SrTiO $_{3}$ (100) using pulsed laser deposition. The 50 nm thick LiCoO $_{2}$ (104) film exhibited lithium (de-)intercalation activity with a first discharge capacity of 119 mAh g $^{-1}$ between 3.0 and 4.4 V, followed by a gradual capacity fading with subsequent charge-discharge cycles. In contrast, a 3.2 nm thick Li $_{3}$ PO $_{4}$ -coated film exhibited a higher intercalation capacity of 148 mAh g $^{-1}$ with superior cycle retention than the uncoated film. In situ surface X-ray diffraction measurements revealed a small lattice change at the coated surface during the (de-)intercalation processes compared to the uncoated surface. The surface modification of LiCoO $_{2}$ by the Li $_{3}$ PO $_{4}$ coating could lead to improvement of the structural stability at the surface region during lithium (de-)intercalation at high voltage.

Journal Articles

Development of non-PGM catalysts for anion exchange membrane fuel cells

Sakamoto, Tomokazu*; Kishi, Hirofumi*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo

Hyomen Kagaku, 37(2), p.78 - 83, 2016/02

https://doi.org/10.1380/jsssj.37.78

We have developed direct liquid fuel anion exchange membrane fuel cell vehicles to deal with the global warming. Non-platinum group metals (PGM) catalyst has been researched to apply for both anode and cathode electrodes. A test driving was carried out for the fuel cell vehicle equipped with no precious metals as catalysts at SPring-8 in 2013. Here we introduce our results of advanced analysis for reaction mechanism and active site of non-PGM catalyst using synchrotron radiation X-rays at SPring-8.

Journal Articles

Structural analysis of electrode-electrolyte interface in lithium batteries

Kanno, Ryoji*; Hirayama, Masaaki*; Suzuki, Kota*; Tamura, Kazuhisa

Hyomen Kagaku, 37(2), p.52 - 59, 2016/02

https://doi.org/10.1380/jsssj.37.52

Batteries are a key technology in today's society. Since the lithium-ion configuration has been widely accepted, significant efforts have been devoted to attain high energy and power densities to produce an excellent energy storage system without any safety issue. To improve the reliability and power characteristics of batteries, deep insights into the reactions at the electrode/electrolyte interface are necessary. The model systems with epitaxial thin-film electrodes might be suitable for understanding these reactions. The in situ techniques for directly observing surface structural changes of the electrodes have been developed for surface X-ray scattering and neutron reflectivity techniques. These techniques are reviewed and future studies on the interfacial reaction in batteries will be discussed.

Journal Articles

Interfacial analysis of surface-coated LiMn $_{2}$ O $_{4}$ epitaxial thin film electrode for lithium batteries

Suzuki, Kota*; Hirayama, Masaaki*; Kim, K.-S.*; Taminato, So*; Tamura, Kazuhisa; Son, J.-Y.*; Mizuki, Junichiro; Kanno, Ryoji*

Journal of the Electrochemical Society, 162(13), p.A7083 - A7090, 2015/08

https://doi.org/10.1149/2.0111513jes

Times Cited Count：8 Percentile：33.81(Electrochemistry)

The effects of surface coatings on LiMn $_{2}$ O $_{4}$ were investigated using LiMn $_{2}$ O $_{4}$ epitaxial thin films with a thickness of 30 nm. Bare and surface-coated LiMn $_{2}$ O $_{4}$ epitaxial thin films were synthesized on SrTiO $_{3}$ (111) substrates using a pulsed laser deposition method. The surface coating, which was formed using the solid electrolyte Li $_{3}$ PO $_{4}$ and had a thickness of 3 nm, improved the reversibility of the electrochemical reactions undergone by the LiMn $_{2}$ O $_{4}$ epitaxial thin films. The changes induced in the surface structure were maintained during battery operation; in contrast, the bare LiMn $_{2}$ O $_{4}$ thin film exhibited structural degradation and Mn dissolution. The structural changes induced in the coated electrode and the increase in its surface stability were intrinsic effects of the Li $_{3}$ PO $_{4}$ coating and improved the electrochemical performance of the LiMn $_{2}$ O $_{4}$ thin-film electrode.

Journal Articles

Operando XAFS study of carbon supported Ni, NiZn, and Co catalysts for hydrazine electrooxidation for use in anion exchange membrane fuel cells

Sakamoto, Tomokazu*; Matsumura, Daiju; Asazawa, Koichiro*; Martinez, U.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; Tamura, Kazuhisa; Nishihata, Yasuo; Tanaka, Hirohisa*

Electrochimica Acta, 163, p.116 - 122, 2015/05

https://doi.org/10.1016/j.electacta.2015.02.156

Times Cited Count：43 Percentile：81.3(Electrochemistry)

Journal Articles

Mechanistic studies on lithium intercalation in a lithium-rich layered material using Li $_{2}$ RuO $_{3}$ epitaxial film electrodes and surface X-ray analysis

Taminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Kim, K.-S.*; Zheng, Y.*; Tamura, Kazuhisa; Mizuki, Junichiro; Kanno, Ryoji*

Journal of Materials Chemistry A, 2(34), p.17875 - 17882, 2014/11

https://doi.org/10.1039/C4TA02795G

Times Cited Count：20 Percentile：60.96(Chemistry, Physical)

The surface structure of a lithium-rich layered material and its relation to intercalation properties were investigated by synchrotron X-ray surface structural analyses using Li $_{2}$ RuO $_{3}$ epitaxial-film model electrodes with different lattice planes of (010) and (001). Electrochemical charge-discharge measurements confirmed reversible lithium intercalation activity through both planes, corresponding to three-dimensional lithium diffusion within the Li $_{2}$ RuO $_{3}$ . The (001) plane exhibited higher discharge capacities compared to the (010) plane under high rate operation (over 5 C). Direct observations of surface structural changes by surface X-ray diffraction (XRD) and surface X-ray absorption near edge structure (XANES) established that an irreversible phase change occurs at the (010) surface during the first (de)intercalation process, whereas reversible structural changes take place at the (001) surface.

Journal Articles

In situ XAFS and HAXPES analysis and theoretical study of cobalt polypyrrole incorporated on carbon (CoPPyC) oxygen reduction reaction catalysts for anion-exchange membrane fuel cells

Asazawa, Koichiro*; Kishi, Hirofumi*; Tanaka, Hirohisa*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Saputro, A. G.*; Nakanishi, Hiroshi*; Kasai, Hideaki*; Artyushkova, K.*; et al.

Journal of Physical Chemistry C, 118(44), p.25480 - 25486, 2014/11

https://doi.org/10.1021/jp507534f

Times Cited Count：13 Percentile：44.39(Chemistry, Physical)

Journal Articles

Origin of the enhancement of electrocatalytic activity and durability of PtRu alloy prepared from a hetero binuclear Pt-Ru complex for methanol oxidation reactions

Okawa, Yukihisa*; Masuda, Takuya*; Uehara, Hiromitsu*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Uosaki, Kohei*

RSC Advances (Internet), 3(35), p.15094 - 15101, 2013/09

https://doi.org/10.1039/c3ra42816h

Times Cited Count：9 Percentile：39.22(Chemistry, Multidisciplinary)

Journal Articles

Structure of Pt(111)/ionomer membrane interface and its bias-induced change in membrane electrode assembly

Masuda, Takuya*; Fukumitsu, Hitoshi*; Kondo, Toshihiro*; Naohara, Hideo*; Tamura, Kazuhisa; Sakata, Osami*; Uosaki, Kohei*

Journal of Physical Chemistry C, 117(23), p.12168 - 12171, 2013/06

https://doi.org/10.1021/jp402251z

Times Cited Count：14 Percentile：48.56(Chemistry, Physical)

The structure of the perfluorosulfonated ionomer (PFSI)/Pt(111) interface in a membrane electrode assembly (MEA)-like configuration of a polymer electrolyte membrane (PEM) fuel cell, that is, a vacuum evaporated Pt layer/PEM(Nafion membrane)/PFSI(adhesion Nafion layer)/Pt(111) single crystal, and its bias-induced change were investigated by surface X-ray scattering measurement at an atomic level. Crystal truncation rod measurement shows that PFSI adsorbed on the Pt(111)-(11) surface without bias. When the Pt(111) electrode was positively biased to form Pt oxide, the PFSI layer was detached from the Pt surface and oxygen atoms penetrated into the Pt lattice.