Mar. 2024, 筑波大学数理物質科学研究群長賞

Apr. 2021, JPS Hot Topics

Mar. 2021, JPSJ Papers of Editors' Choice

Mar. 2021, 筑波大学数理物質科学研究科物理学専攻長賞

Aug. 2020, 第8回TIAナノグリーン・サマースクール優秀賞

Concentration gradient effect in liquid thermoelectric device composed of organic-solvent-added aqueous solution containing K₄[Fe(CN)₆]/K₃[Fe(CN)₆]
Yuudai Tanaka; Akihiro Wake; Dai Inoue; Yutaka Moritomo, Abstract

A liquid thermoelectric conversion device (LTE), which has a simple device structure composed of low-cost materials, is attracting attention. Here, we investigated the additive effect of methanol (MeOH), acetone, and tetrahydrofuran (THF) on an LTE composed of a K₄[Fe(CN)₆]/K₃[Fe(CN)₆] aqueous solution. We  ascribed to the enhancement of the thermal voltage V and electrochemical Seebeck coefficient α to precipitation of K₄[Fe(CN)₆] and resultant concentration gradient of [Fe(CN)₆]³⁻ between the hot and cold electrodes. The enhancement of V and α is quantitatively reproduced by the concentration gradient model incorporating experimentally-obtained solubility s(T) of K₄[Fe(CN)₆]. We further demonstrated that precipitation enhances the maximum power by as much as 152% in a MeOH-added LTE composed of 0.35 M K₄[Fe(CN)₆]/K₃[Fe(CN)₆] aqueous solution at ΔT = 10 K., IOP Publishing
Japanese Journal of Applied Physics, 01 Jan. 2024, [Reviewed]

Coated electrodes for liquid thermoelectric conversion devices to enhance Fe²⁺/Fe³⁺ redox kinetics
Touya Aiba; Dai Inoue; Yutaka Moritomo, A graphite-dispersion coated electrode enhances the output power of a LTE by 37.5% as compared with that of a LTE composed of a conventional graphite sheet., Royal Society of Chemistry (RSC)
Sustainable Energy & Fuels, 2024, [Reviewed]

Precipitation enhancement of liquid thermoelectric conversion with Fe(ClO₄)₂/Fe(ClO₄)₃ dissolved in DMF
Akihiro Wake; Dai Inoue; Yutaka Moritomo, Oxidant precipitation in the electrolyte significantly enhances the open circuit voltage and output power in a liquid thermoelectric conversion device., Royal Society of Chemistry (RSC)
Energy Advances, 2024, [Reviewed]

Concentration dependence of resistance components in solutions containing dissolved Fe²⁺/Fe³⁺
Dai Inoue; Yutaka Moritomo, Lead, The concentration (c) dependence of solution (R_s) and diffusion (R_dif) resistances of solutions containing dissolved Fe²⁺/Fe³⁺ is well reproduced by their viscosity η(c) at c., Royal Society of Chemistry (RSC)
RSC Advances, 2024, [Reviewed]

Resistance components in organic electrolytes containing Fe²⁺/Fe³⁺ for liquid thermoelectric conversion devices
Yunika Nomura; Dai Inoue; Yutaka Moritomo, The solution resistance R_s of an organic electrolyte containing 0.1 M Fe²⁺/Fe³⁺ is proportional to the viscosity η of the solvent, but the slope depends on the complex species., Royal Society of Chemistry (RSC)
New Journal of Chemistry, 2023, [Reviewed]

Temperature switch of electrochemical Seebeck coefficient of Fe²⁺/Fe³⁺via formation of [FeCl₄]²⁻/[FeCl₄]⁻
Yunika Nomura; Dai Inoue; Yutaka Moritomo, Temperature change switches the electrochemical Seebeck coefficient (α) of Fe²⁺/Fe³⁺via transformation of the electrochemically-active redox pair., Royal Society of Chemistry (RSC)
RSC Advances, 2023, [Reviewed]

Liquid thermoelectric conversion devices composed of several organic solvents
Akihiro Wake; Dai Inoue; Yutaka Moritomo, Abstract

We evaluated the performances of liquid thermoelectric conversion devices (LTEs) composed of nine organic solvents containing an Fe²⁺/Fe³⁺ redox pair against the electrolyte concentration (m). In protic solvents, i.e. methanol (Me), ethanol (Et), 1-propanol (Pr), and ethylene glycol (EG), the electrochemical Seebeck coefficient (α = dV/dT, where V and T are the electrode potential and temperature, respectively) increases with m in the small m region. Based on the ultraviolet—visible absorption spectroscopy, we interpreted the enhancement of α in terms of the OH⁻ and/or H₂O coordination to Fe³⁺, which was introduced by the crystal water of the solute. At a temperature difference (ΔT) of 30 K, the maximum value of the power factor of the Me LTE reaches 11.5 μW K⁻²m., IOP Publishing
Japanese Journal of Applied Physics, 23 Dec. 2022, [Reviewed]

Local structure of Fe²⁺ and Fe³⁺ in organic solvents
Dai Inoue; Toshiki Komatsu; Hideharu Niwa; Hiroaki Nitani; Hitoshi Abe; Yutaka Moritomo, Lead, Abstract

We systematically investigated the local structure of Fe²⁺ and Fe³⁺ in 11 solvents by extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge structure (XANES). The EXAFS analyses with a one-shell model indicate that Fe²⁺ and Fe³⁺ are coordinated by six oxygen of the ligand molecules (L) and form a FeL₆-type complex in all solvents. The XANES suggests that the [FeL₆]³⁺ complex shows noncentrosymmetric deformation in several solvents. In protic solvents, the EXAFS analyses with a two-shell model revealed that the coordination number (n_C) of the second nearest carbon around Fe³⁺ significantly depends on L. We interpreted the observation in terms of the distribution of the Fe-C distance., IOP Publishing
Japanese Journal of Applied Physics, 18 Oct. 2022, [Reviewed]

Coordination States of Fe³⁺ and Fe²⁺ Dissolved in Organic Solvents
Dai Inoue; Toshiki Komatsu; Hideharu Niwa; Toshiaki Ina; Hiroaki Nitani; Hitoshi Abe; Yutaka Moritomo, Lead, Physical Society of Japan
Journal of the Physical Society of Japan, 15 Sep. 2022, [Reviewed]

Electrochemical Seebeck coefficient of Fe²⁺/Fe³⁺ in acetone–methanol mixed solution
Toshiki Komatsu; Dai Inoue; Yutaka Moritomo, Abstract

The electrochemical Seebeck coefficient (α) of Fe²⁺/Fe³⁺ in acetone–methanol (MeOH) mixed solution was systematically investigated against the acetone molar ratio (n) and molar ratio of Fe³⁺ to Fe (n_Fe3+). At n_Fe3+ = 0.75, α monotonously increases with increase in n from 0.3 mV K⁻¹ at n = 0.00 to 3.4 mV K⁻¹ at n = 1.00. At n_Fe3+ = 0.50 and 0.25, we found anomalous dip structures in the n−α plot at n ≈ 0.9 and 0.4, respectively. Based on a spectroscopic investigation, we interpreted the observed dip structures in terms of the transition state between the FeCl₄-active and FeL₆-active regions., IOP Publishing
Japanese Journal of Applied Physics, 23 May 2022, [Reviewed]

A liquid thermoelectric device composed of organic solution
Akihiro Wake; Dai Inoue; Yutaka Moritomo, Abstract

The liquid thermoelectric device (LTE) exhibits a very simple structure that consists of hot/cold electrodes of identical type and a solution with a redox couple. Here, we evaluated the performances of LTE composed of acetone (or acetonitrile) solutions of Fe(ClO₄)₂/Fe(ClO₄)₃ against their concentration (m). The electrochemical Seebeck coefficients (α) of organic LTE range from 1.5 to 2.5 mV K⁻¹ and are higher than α (=1.4 mV K⁻¹) of the corresponding aqueous LTE. The dimensionless figure of merit (ZT) of organic LTE is ≈0.015 at maximum and is higher than the maximum ZT (=0.009) of the corresponding aqueous LTE. Thus, the organic LTE is promising as an energy harvesting device., IOP Publishing
Applied Physics Express, 13 Apr. 2022, [Reviewed]

Control of Fe³⁺ coordination by excess Cl⁻ in alcohol solutions
Yunika Nomura; Dai Inoue; Yutaka Moritomo, Fe³⁺ coordination in alcohol solution can be controlled by the Cl⁻ concentration ([Cl⁻]). The coordination state changes from FeL₆ (L: solvent molecule) to FeCl₄ type via FeCl_nL_6−n with increases in [Cl⁻]., Royal Society of Chemistry (RSC)
RSC Advances, 2022, [Reviewed]

Origin of the Material Dependence of the Temperature Coefficient of the Redox Potential in Coordination Polymers
Yutaka Moritomo; Yuma Yoshida; Dai Inoue; Hiroki Iwaizumi; Shintaro Kobayashi; Shogo Kawaguchi; Takayuki Shibata, Physical Society of Japan
Journal of the Physical Society of Japan, 15 Jun. 2021, [Reviewed]

Scaling Relation between Electrochemical Seebeck Coefficient for Fe²⁺/Fe³⁺ in Organic Solvent and Its Viscosity
Dai Inoue; Hideharu Niwa; Hiroaki Nitani; Yutaka Moritomo, Lead, Physical Society of Japan
Journal of the Physical Society of Japan, 15 Mar. 2021, [Reviewed]

Origin of the material dependence of temperature coefficient of redox potential in conjugated polymers
Hiroki Iwaizumi; Dai Inoue; Takeshi Yasuda; Yutaka Moritomo, Abstract

The thermal coefficient α (=dV/dT) of the redox potential (V) is an important physical parameter for thermal energy harvesting. To clarify the microscopic origin of α in conjugated polymers, we compared α and the physical quantity obtained by a quantum chemistry calculation in typical polymers with small monomer molecular weight. We observed a strong correlation between α and the number (N_active) of the active atom, which is defined as the atom whose variation of the Mulliken charge (Δq) at the oxidation process is beyond a threshold (Δq_th). We interpreted the material dependence of α in terms of N_active, because active atoms have a significant effect on the configuration entropy of the surrounding solvent molecules., IOP Publishing
Applied Physics Express, 23 Feb. 2021, [Reviewed]

Structural Phase Transition Triggered by Na Ordering in Na_1.96Cd[Fe(CN)₆]_0.99
Yutaka Moritomo; Yuma Yoshida; Hiroki Iwaizumi; Dai Inoue; Ichiro Nagai; Takayuki Shibata, Physical Society of Japan
Journal of the Physical Society of Japan, 15 Jan. 2021, [Reviewed]

Volume effect of organic solvent on electrochemical Seebeck coefficient of [Fe(CN)₆]⁴⁻/[Fe(CN)₆]³⁻ in water
Dai Inoue; Yuya Fukuzumi; Yutaka Moritomo, Lead, IOP Publishing
Japanese Journal of Applied Physics, 28 Feb. 2020, [Reviewed]

Influence of microfabrication on superconducting properties of exfoliated thin films of layered superconductor NbSe₂: reactive ion etching
Hikari Tomori; Naoki Hoshi; Dai Inoue; Akinobu Kanda, IOP Publishing
Journal of Physics: Conference Series, 01 Sep. 2019, [Reviewed]

Response of a superconductor NbSe₂ flake to magnetic field detected with small tunnel junctions
Naoki Hoshi; Dai Inoue; Hiroki Sonoda; Daisuke Yabe; Hikari Tomori; Akinobu Kanda, Abstract

We have experimentally studied response of a superconductor NbSe₂ flake to perpendicular magnetic fields using small tunnel junctions. The NbSe₂ film (lateral size ∼ several μm, thickness ∼ 50 nm) was obtained using the mechanical exfoliation of a bulk crystal and was transfered on top of predefined Au electrodes, forming an Au/NbSe₂/Au double SIN tunnel junction system. At 4.2 K, between the lower and upper critical fields (H_C1 and H_C2), the voltage of the Au/NbSe₂/Au structure under constant current of 1 μA exhibited random-telegraph-noise-like fluctuations as a function of the magnetic field which was applied perpendicular to the NbSe₂ flake. The origin of the voltage fluctuations is discussed., IOP Publishing
Journal of Physics: Conference Series, 01 Sep. 2019, [Reviewed]

Influence of focused-ion-beam microfabrication on superconducting transition in exfoliated thin films of layered superconductor NbSe₂
Hikari Tomori; Naoki Hoshi; Dai Inoue; Akinobu Kanda, Abstract

We have experimentally studied the influence of the focused ion beam (FIB) microfabrication on the superconducting properties of exfoliated thin films of layered superconductor NbSe₂ through transport measurement. We observed significant decrease of the residual-resistance ratio (RRR), indicating the formation of defects by the FIB. Although clear superconducting transition was seen before the FIB microfabrication, after FIB it was blurred, and one sample exhibited insulating behavior. The possible origins of the changes in the superconducting properties are discussed., IOP Publishing
Journal of Physics: Conference Series, 01 Sep. 2019, [Reviewed]

Fe イオンが溶解した有機溶媒の溶媒構造　　　　　　　　　　　　　　　
森 義浩; 宮間 遼; 井上 大
令和6年度 電気学会東京支部茨城支所研究発表会, 30 Nov. 2024

Fe2+ / Fe3+ MeOH 溶液における添加剤による出力向上　　　　　　　　　　　　　　　
宮間 遼; 森 義浩; 井上 大
令和6年度 電気学会東京支部茨城支所研究発表会, 30 Nov. 2024

液体熱電変換素子のための塗布型電極　　　　　　　　　　　　　　　
相羽憧也; 井上大; 守友浩
第71回応用物理学会春季学術講演会, Mar. 2024

[Fe(CN)6]4-/[Fe(CN)6]3-水溶液の熱起電力における析出効果　　　　　　　　　　　　　　　
田中雄大; 和氣暁大; 井上大; 守友浩
第71回応用物理学会春季学術講演会, Mar. 2024

Fe2+/Fe3+有機溶媒溶液の抵抗成分　　　　　　　　　　　　　　　
井上大; 守友浩
第71回応用物理学会春季学術講演会, Mar. 2024

Fe2+/Fe3+対を含む有機溶液の抵抗成分　　　　　　　　　　　　　　　
野村由仁香; 井上大; 守友浩
第84回応用物理学会秋季学術講演会, Sep. 2023

Fe2+/Fe3+DMF溶液における電気化学ゼーベック係数の析出駆動効果　　　　　　　　　　　　　　　
和氣暁大; 井上大; 守友浩
第84回応用物理学会秋季学術講演会, Sep. 2023

Fe2+/Fe3+溶液の抵抗成分の濃度依存性　　　　　　　　　　　　　　　
井上大; 野村由仁香; 和氣暁大; 守友浩
第84回応用物理学会秋季学術講演会, Sep. 2023

FeCl4錯体の形成による電気化学ゼーベック係数の制御　　　　　　　　　　　　　　　
野村由仁香; 井上大; 守友浩
第70回応用物理学会春季学術講演会, Mar. 2023

アセトンーエタノール混合溶液中のFe2+/Fe3+の電気化学ゼーベック係数　　　　　　　　　　　　　　　
小松俊輝; 井上大; 守友浩
第83回応用物理学会秋季学術講演会, Sep. 2022

Fe2+/Fe3+酸化還元対を活用した熱電変換　　　　　　　　　　　　　　　
和氣暁大; 井上大; 守友浩
第83回応用物理学会秋季学術講演会, Sep. 2022

鉄イオンの配位状態の溶媒依存性　　　　　　　　　　　　　　　
井上大; 小松俊輝; 丹羽秀治; 仁谷浩明; 阿部仁; 守友浩
第83回応用物理学会秋季学術講演会, Sep. 2022

塩素を添加されたアルコール溶媒中のFeCl4錯体の形成　　　　　　　　　　　　　　　
野村由仁香; 井上大; 守友浩
第69回応用物理学会春季学術講演会, Mar. 2022

Fe2+/Fe3+酸化還元対を活用した熱電変換　　　　　　　　　　　　　　　
和氣暁大; 井上大; 守友浩
第69回応用物理学会春季学術講演会, Mar. 2022

有機溶媒に溶解した鉄イオンの配位状態　　　　　　　　　　　　　　　
井上大; 小松俊輝; 丹羽秀治; 伊奈稔哲; 仁谷浩明; 阿部仁; 守友浩
第69回応用物理学会春季学術講演会, Mar. 2022

プルシャンブル―類似体の酸化還元電位の温度係数の決定要因　　　　　　　　　　　　　　　
守友浩; 吉田悠馬; 井上大; 岩泉滉樹; 小林慎太郎; 河口彰吾; 柴田恭幸
第82回応用物理学会秋季学術講演会, Sep. 2021

高分子の酸化還元ポテンシャルの温度係数の起源　　　　　　　　　　　　　　　
岩泉滉樹; 井上大; 安田剛; 守友浩
第68回応用物理学会春季学術講演会, Mar. 2021

Fe2+/Fe3+有機溶媒溶液における電気化学ゼーベック係数と粘性率とのスケール則　　　　　　　　　　　　　　　
井上大; 丹羽秀治; 仁谷浩明; 守友浩
第68回応用物理学会春季学術講演会, Mar. 2021

電気化学ゼーベック係数における有機分子の添加効果　　　　　　　　　　　　　　　
井上大; 福住勇矢; 守友浩
第81回応用物理学会秋季学術講演会, Sep. 2020

Apr. 2025 - Present

Apr. 2025 - Present

Apr. 2025 - Present

Apr. 2024 - Mar. 2025

Dec. 2019 - Present, 応用物理学会

添加剤効果による液体熱電変換のミクロ－マクロ物理量の相関解明　　　　　　　　　　　　　　　
Apr. 2025 - Mar. 2027

自律型独立分散電源への社会実装に向けた環境熱電変換デバイス　　　　　　　　　　　　　　　
Sep. 2024 - Aug. 2026

有機溶媒に溶解した Fe イオン近傍・中距離クラスター構造の解明　　　　　　　　　　　　　　　
Apr. 2025 - Mar. 2026

アルコール溶液に溶解した遷移金属イオン近傍の局所構造解析　　　　　　　　　　　　　　　
Apr. 2025 - Mar. 2026

巨大電気化学ゼーベック係数材料系創出を目指した酸化還元対エンジニアリング　　　　　　　　　　　　　　　
Apr. 2025 - Mar. 2026

添加剤効果による液体熱電変換の微視的理解および高効率材料系開発　　　　　　　　　　　　　　　
Apr. 2024 - Mar. 2025

混合溶媒系の電気化学ゼーベック係数の微視的理解と巨大化
特別研究員奨励費
筑波大学
Mar. 2022 - Mar. 2024