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Development of hydrogen oxidation reaction catalysts to overcome CO poisoning and elucidation of reaction mechanism

稲川 康平*; 松村 大樹; 谷口 昌司*; 上垣 伸弥*; 中山 智仁*; 浦野 純乃介*; 青谷 拓朗*; 田中 裕久*

Journal of Physical Chemistry C, 127(24), p.11542 - 11549, 2023/06

Passive autocatalytic recombiner (PAR) represents a potential technology for ensuring process safety in the hydrogen society. PARs function through the catalytic oxidation of generated or leaked hydrogen, facilitating its conversion into water and effectively mitigating the risk of hydrogen explosions. CO is recognized as a catalyst poison that hampers surface catalytic reactions. To investigate the negative effects of CO on the local structure of platinum metal nanoparticle catalysts during water formation, in situ and time-resolved X-ray absorption spectroscopy analyses were conducted. The results revealed that the Pt-Fe/CZY catalyst exhibited notable hydrogen oxidation activity even in the presence of CO. The enhanced performance can be attributed to the combined effects of Pt-Fe alloy composition and CZY support materials.


Investigation of hydrogen superoxide adsorption during ORR on Pt/C catalyst in acidic solution for PEFC by ${it in-situ}$ high energy resolution XAFS

山本 直生*; 松村 大樹; 萩原 悠人*; 田中 啓偉*; 長谷川 優太*; 石井 賢司*; 田中 裕久*

Journal of Power Sources, 557, p.232508_1 - 232508_10, 2023/02

 被引用回数:0 パーセンタイル:0.01(Chemistry, Physical)

Oxygen Reduction Reaction (ORR) is one of the key electrochemical reactions, especially in Polymer Electrolyte Fuel Cells (PEFCs). In this work, the reaction pathway and intermediate species such as molecular-type oxygen during ORR were discussed. High energy resolution X-ray absorption fine structure spectra at the Pt L$$_{3}$$-edge were obtained to observe the electronic structure of Pt catalyst. Carbon-supported Pt nanoparticles as powder catalysts were used for measurement as more realistic conditions, and the species adsorbed on the Pt nanoparticles were analyzed while controlling under the potentials in acidic electrolyte solution with N$$_{2}$$ or O$$_{2}$$ gas bubbling. Molecular-type oxygen adsorption species is observed only in the O$$_{2}$$-bubbled electrolyte solution. This intermediate adsorption species is assigned to a hydrogen superoxide.


${it Operando}$ structure observation of pyroelectric ceramics during power generation cycle

川崎 卓郎; 福田 竜生; 山中 暁*; 坂本 友和*; 村山 一郎*; 加藤 孝典*; 馬場 将亮*; 橋本 英樹*; Harjo, S.; 相澤 一也; et al.

Journal of Applied Physics, 131(13), p.134103_1 - 134103_7, 2022/04

 被引用回数:1 パーセンタイル:26.82(Physics, Applied)

The microscopic origin of the pyroelectric power generation using ferroelectric ceramics for energy harvesting from time-varying waste heat can be understood by conducting ${it operando}$ neutron diffraction measurements. The behavior of the domain orientation and lattice strain in the lead zirconate titanate (PZT)-based ceramics with a tetragonal structure during the novel power generation cycle combining electric field and temperature change were investigated. The [001] domains and the lattice strain of the (111) plane in the direction of parallel to the electric field increase in the process of simultaneous rise in the electric field and temperature, and rapidly decrease in the process of the field drop. The alignment of the domain orientation by the electric field and its randomization by the higher temperature during the cycle are critical features of the current power generation system.


An Automotive intelligent catalyst that contributes to hydrogen safety for the Decommissioning of Fukushima Daiichi Nuclear Power Station (1FD)

田中 裕久*; 正木 清香*; 青谷 拓朗*; 稲川 康平*; 岩田 宗悟*; 相田 樹哉*; 山本 忠亮*; 喜多 知輝*; 大野 瞳*; 竹中 啓恭*; et al.

SAE Technical Paper 2022-01-0534 (Internet), 10 Pages, 2022/03

The catalyst called a Passive Autocatalytic Recombiner (PAR) is required to have robustness that can maintain its activity for more than 30 years in an environment where temperature, humidity, gas concentration, etc. cannot be controlled. Here, it is expected that "An Intelligent Catalyst" for automotive emissions control exhibits excellent performance even in such a harsh environment. The intelligent catalyst is the nanostructure designed perovskite catalyst that has the rejuvenating function instead of preventing aging. The authors emphasize that the technology developed as a catalyst for automobiles is expected to be useful not only in other industries but also as a relief technology from the national crisis.


Performance tests of catalysts for the safe conversion of hydrogen inside the nuclear waste containers in Fukushima Daiichi

Reinecke, E.-A.*; 竹中 啓恭*; 大野 瞳*; 喜多 知輝*; 谷口 昌司*; 西畑 保雄; 日野 竜太郎; 田中 裕久*

International Journal of Hydrogen Energy, 46(23), p.12511 - 12521, 2021/03

 被引用回数:4 パーセンタイル:28(Chemistry, Physical)

安全な廃炉は福島第一原子力発電所の事故による放射性物質の除染同様に今後の大きな課題である。現在、廃棄物長期保管容器の研究開発は日本の国際協力における緊急の課題となっている。容器中の放射線分解による大量の水素と酸素は、海水を含んでいるために問題となっている。放射線分解による可燃性ガスの発生は容器の内圧を上昇させ、引火による設備の健全性喪失のリスクとなる。日本の文部科学省のプロジェクト「廃棄物長期保管容器内に発生する可燃性ガスの濃度低減技術に関する研究開発」では、保管容器内における水素再結合触媒装置の適用可能性について調べた。ここで適用したのは、インテリジェント触媒と呼ばれており、自動車排ガス浄化用の大量生産のために開発されたもので、Pd, Pt, Rhの貴金属がペロブスカイト酸化物中に固溶しており、自己再生機能を有している。水素再結合触媒評価装置REKO-4によって、触媒の基本的な特性を評価した。


Pyroelectric power generation from the waste heat of automotive exhaust gas

Kim, J.*; 山中 暁*; 村山 一郎*; 加藤 孝典*; 坂本 友和*; 川崎 卓郎; 福田 竜生; 関野 徹*; 中山 忠親*; 武田 雅敏*; et al.

Sustainable Energy & Fuels (Internet), 4(3), p.1143 - 1149, 2020/03

 被引用回数:15 パーセンタイル:66.91(Chemistry, Physical)

Waste heat is a potentially exploitable energy source but remains a problem awaiting a solution. To explore solutions for automobile applications, we investigate pyroelectric power generation from the temperature variation of exhaust gas using a novel electro-thermodynamic cycle. Niobium-doped lead zirconate titanate stannate (PNZST) ceramics were applied as pyroelectric materials, and their structural characteristics were investigated. In the driving cycle assessments (JC-08) using real exhaust gas, the maximum power generated was identified as 143.9 mW cm$$^{-3}$$ (777.3 J L$$^{-1}$$ per 1 cycle) over a temperature range of 150-220 $$^{circ}$$C and an electric field of 13 kV cm-1. The net mean generating power of the total driving cycle was 40.8 mW cm$$^{-3}$$, which is the most enhanced result in our power generating systems to date and 314 times greater than our first report. Materials with sharp transition behaviors with the temperature and electric field are worthy of study with regard to pyroelectric energy harvesting materials, and their corresponding crystal and domain structures were investigated to optimize performance.


Research on hydrogen safety technology utilizing the automotive catalyst

大野 瞳*; 竹中 啓恭*; 喜多 知輝*; 谷口 昌司*; 松村 大樹; 西畑 保雄; 日野 竜太郎; Reinecke, E.-A.*; 高瀬 和之*; 田中 裕久*

E-Journal of Advanced Maintenance (Internet), 11(1), p.40 - 45, 2019/05

Safety management technology of hydrogen gas is extremely important not only for nuclear power generation but also for future society. A brand-new passive autocatalytic recombiner (PAR) system utilizing the monolithic "intelligent catalyst" has been studied for the long-term storage of high-concentration radioactive materials related to the decommissioning of nuclear reactors. The monolith-type automotive catalyst showed high hydrogen conversion activity from a room temperature in a large scale reactor of REKO-4. It became clear that natural convection by reaction is greatly improved by roughening the cell density of the monolith catalyst especially under static environmental conditions such as in a storage container. Taking advantage of this superior catalytic property, we aim to complete the safety technology for storage containers at an early stage and advance the development of highly active catalyst from further low temperature.


Electrochemical adsorption on Pt nanoparticles in alkaline solution observed using in situ high energy resolution X-ray absorption spectroscopy

草野 翔吾*; 松村 大樹; 石井 賢司*; 田中 裕久*; 水木 純一郎*

Nanomaterials (Internet), 9(4), p.642_1 - 642_14, 2019/04

 被引用回数:6 パーセンタイル:35.38(Chemistry, Multidisciplinary)

The oxygen reduction reaction (ORR) on Pt/C in alkaline solution was studied by in situ high energy resolution X-ray absorption spectroscopy. To discuss the X-ray absorption near-edge structure (XANES), this paper introduced the rate of change of the $$Delta mu$$ (RCD), which is an analysis method that is sensitive to surface adsorption. The surface adsorptions as hydrogen (below 0.34 V), superoxide anion (from 0.34 V to 0.74 V), hydroxyl species (from 0.44 V to 0.74 V), atomic oxygen (above 0.74 V), and $$alpha$$-PtO$$_{2}$$ (above 0.94 V) were distinguished. It is clarified that the catalytic activity in an alkaline solution is enhanced by the stability of atomic oxygen and the low stability of superoxide anion/peroxide adsorption on the platinum surface.


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

岸 浩史*; 坂本 友和*; 朝澤 浩一郎*; 山口 進*; 加藤 豪士*; Zulevi, B.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; 松村 大樹; et al.

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

 被引用回数:10 パーセンタイル:48.06(Chemistry, Multidisciplinary)

Platinum group metal-free catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of in situ X-ray spectroscopy techniques, high-resolution transmission electron microscope, M$"o$ssbauer spectroscopy, electrochemical methods and density functional theory. Fe-N-C oxygen reduction reaction electrocatalysts were synthesized by varying several synthetic parameters to obtain nanomaterials with different composition and morphology. Associated with Fe-N$$_x$$ motive and the presence of Fe metallic particles in the electrocatalysts showed the clear differences in the variation of composition; processing and treatment conditions of sacrificial support method. From the results of material characterization; catalytic activity and theoretical studies; Fe metallic particles (coated with carbon) are main contributors into the HO$$_{2}$$$$^{-}$$ generation.


Electrical and crystallographic study of an electrothermodynamic cycle for a waste heat recovery

Kim, J.*; 山中 暁*; 中島 啓*; 加藤 孝典*; Kim, Y.*; 福田 竜生; 吉井 賢資; 西畑 保雄; 馬場 将亮*; 武田 雅敏*; et al.

Advanced Sustainable Systems (Internet), 2(11), p.1800067_1 - 1800067_8, 2018/11

 被引用回数:7 パーセンタイル:29.36(Green & Sustainable Science & Technology)

An innovative electrothermodynamic cycle (pyroelectric effect with an external electric field) was recently presented, which is based on temporal temperature variations in wasted heat from engine exhaust gas. In this paper, for further improvement, a generating mechanism of the cycle is investigated using in-operando time-resolved synchrotron X-ray diffraction with generating assessment. The polarizations of the sample are gained from both crystal/domain changes and simultaneous electrical measurements. Three types of materials are prepared: soft and hard types of lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-PT). Among them, PMN-PT has the highest generating power. When an external electric field is applied, the PMN-PT exhibits only 180$$^circ$$ domain rotations, whereas PZTs exhibit both 90$$^circ$$ and 180$$^circ$$ rotations. A strong driving force for 180$$^circ$$ rotation depresses rotations in other angles and increases polarization changes. The results show that the material development, which has only 180$$^circ$$ switching domains, has potential for use in the establishment of a high-efficiency waste heat recovery system.


Temperature stability of PIN-PMN-PT ternary ceramics during pyroelectric power generation

茂呂 拓哉*; Kim, J.*; 山中 暁*; 村山 一郎*; 加藤 孝典*; 中山 忠親*; 武田 雅敏*; 山田 昇*; 西畑 保雄; 福田 竜生; et al.

Journal of Alloys and Compounds, 768, p.22 - 27, 2018/11

 被引用回数:17 パーセンタイル:68.65(Chemistry, Physical)

Relaxor-based ternary Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_3$$-Pb(Mg$$_{1/3}$$Nb$$_{2/3}$$)O$$_3$$-PbTiO$$_3$$ (PIN-PMN-PT) ceramics near a morphotropic phase boundary were grown, and their electrical properties at various temperatures were investigated in the electrothermodynamic cycle for the future environment-friendly automotive applications. Structural disordering, depending on the PIN content, influenced the diffuse phase transition between the tetragonal and cubic structures and contributed to the power-generating behavior. The net power-generating energies (P$$_{net}$$) were 2.43-3.01 mW/cm$$^3$$ at temperatures above 200$$^circ$$C and were maintained at above 1 mW/cm$$^3$$ over a temperature range of approximately 100 degrees. Therefore, the PIN-PMN-PT system has a possibility of a wider usage temperature range, the disordering of the perovskite crystal structure can be controlled, and it will be a candidate for the application of pyroelectric energy conversion system.


Development of radiation resistant monitoring camera system

武内 伴照; 大塚 紀彰; 渡辺 恭志*; 田中 茂雄*; 小沢 治*; 駒野目 裕久*; 上野 俊二*; 土谷 邦彦

Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 3 Pages, 2018/11



Pyroelectric power generation with ferroelectrics (1-x)PMN-xPT

Kim, J.*; 山中 暁*; 中島 啓*; 加藤 孝典*; Kim, Y.*; 福田 竜生; 吉井 賢資; 西畑 保雄; 馬場 将亮*; 武田 雅敏*; et al.

Ferroelectrics, 512(1), p.92 - 99, 2017/08

 被引用回数:14 パーセンタイル:57.51(Materials Science, Multidisciplinary)

We have been investigating a novel electrothermodynamic cycle based on temporal temperature variations using the pyroelectric effect to utilize the waste heat as renewable energy. An improved generating performance with relaxer ferroelectric ceramics was achieved using 75Pb(Mg$$_{2/3}$$Nb$$_{1/3}$$)O$$_3$$-25PbTiO$$_3$$ which is well known for the high dielectric and pyroelectric properties. The potential was evaluated by using the hysteresis loops and generating properties are analyzed both in laboratory and engine dynamometer. Results showed 0.48 mW/cm$$^3$$ in engine dynamometer assessment, which is 3 times larger than the previous study using Pb(Zr,Ti)O$$_3$$.


Study of catalytic reaction at electrode-electrolyte interfaces by a CV-XAFS method

草野 翔吾*; 松村 大樹; 朝澤 浩一郎*; 岸 浩史*; 坂本 友和*; 山口 進*; 田中 裕久*; 水木 純一郎*

Journal of Electronic Materials, 46(6), p.3634 - 3638, 2017/06

 被引用回数:3 パーセンタイル:20.49(Engineering, Electrical & Electronic)

A method combining cyclic voltammetry (CV) with X-ray absorption fine structure (XAFS) spectroscopy, viz. CV-XAFS, has been developed to enable in situ real-time investigation of atomic and electronic structures related to electrochemical reactions. We use this method to study the reaction of a Pt/C cathode catalyst in the oxygen reduction reaction (ORR) in an alkaline electrolyte. It was found that the current induced by the ORR was first observed at approximately 0.08 V versus Hg/HgO, although the Pt valence remained almost unchanged. The electronic structure of the catalytic surface in the ORR was observed to be different in the negative and positive scan directions of CV measurements. Hydrogen adsorption is also discussed on the basis of the observation of this spectral change. We have demonstrated that CV-XAFS provides dynamical structural and electronic information related to electrochemical reactions and can be used for in situ real-time measurements of a catalyst.


Relationship between the material properties and pyroelectric-generating performance of PZTs

山中 暁*; Kim, J.*; 中島 啓*; 加藤 孝典*; Kim, Y.*; 福田 竜生; 吉井 賢資; 西畑 保雄; 馬場 将亮*; 山田 昇*; et al.

Advanced Sustainable Systems (Internet), 1(3-4), p.1600020_1 - 1600020_6, 2017/04



${{it In situ}}$ X-ray absorption spectroscopy study on water formation reaction of palladium metal nanoparticle catalysts

松村 大樹; 谷口 昌司*; 田中 裕久*; 西畑 保雄

International Journal of Hydrogen Energy, 42(11), p.7749 - 7754, 2017/03

 被引用回数:6 パーセンタイル:17.35(Chemistry, Physical)

Proper management of hydrogen gas is extremely important for the safety security of nuclear power plants. Hydrogen removal by the water formation reaction on a catalyst is one of the candidates for creating hydrogen safety system. We observed in situ and real-time-resolved structure change of palladium metal nanoparticles during the water formation reaction by using X-ray absorption spectroscopy technique. The effect of carbon monoxide poisoning on catalytic activity was also studied. We have found that the creation of oxidized surface layer on palladium metal nanoparticles plays an important role of the water formation reaction process.


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

坂本 友和*; 増田 晃之*; 吉本 光児*; 岸 浩史*; 山口 進*; 松村 大樹; 田村 和久; 堀 彰宏*; 堀内 洋輔*; Serov, A.*; et al.

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

 被引用回数:12 パーセンタイル:42.46(Electrochemistry)

NiO/ Nb$$_{2}$$O$$_{5}$$/C (8:1), (4:1), (2:1), NiO/C, and Ni/C catalysts for hydrazine electrooxidation were synthesized by an evaporation drying method followed by thermal annealing. Prepared catalysts were characterized by X-ray diffraction (XRD), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectrometry (EDS), and X-ray absorption fine structure (XAFS). The highest catalytic activity in mentioned above reactionwas found for Ni/C, followed by: NiO/Nb$$_{2}$$O$$_{5}$$/C (8:1), NiO/Nb$$_{2}$$O$$_{5}$$/C (4:1). NiO/Nb$$_{2}$$O$$_{5}$$/C (2:1) whiles NiO/C has almost no activity for hydrazine oxidation. It was explained by oxygen defect of NiO in NiO/ Nb$$_{2}$$O$$_{5}$$/C from XAFS analysis. The selectivity hydrazine electrooxidation as measured by ammonia production resulted in observation that metallic Ni surface facilitates N-N bond breaking of hydrazine, which was confirmed by density functional theory (DFT) calculations.


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

坂本 友和*; 岸 浩史*; 山口 進*; 松村 大樹; 田村 和久; 堀 彰宏*; 堀内 洋輔*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; et al.

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

 被引用回数:28 パーセンタイル:75.78(Electrochemistry)

The catalytic process takes place on nickel oxide surface of a Ni oxide nano-particle decorated carbon support (NiO/C). In-situ X-ray absorption fine structure (XAFS) spectroscopy was used to investigate the reaction mechanism for hydrazine electrooxidation on NiO surface. The spectra of X-ray absorption near-edge structure (XANES) of Ni K-edge indicated that adsorption of OH$$^{-}$$ on Ni site during the hydrazine electrooxidation reaction. Density functional theory (DFT) calculations were used to elucidate and suggest the mechanism of the electrooxidation and specifically propose the localization of electron density from OH$$^{-}$$ to 3d orbital of Ni in NiO. It is found that the accessibility of Ni atomic sites in NiO structure is critical for hydrazine electrooxidation. Based on this study, we propose a possible reaction mechanism for selective hydrazine electrooxidation to water and nitrogen taking place on NiO surface as it is applicable to direct hydrazine alkaline membrane fuel cells.



武内 伴照; 大塚 紀彰; 土谷 邦彦; 田中 茂雄*; 小沢 治*; 駒野目 裕久*; 渡辺 恭志*; 上野 俊二*

日本保全学会第13回学術講演会要旨集, p.391 - 394, 2016/07




坂本 友和*; 岸 浩史*; 山口 進*; 田中 裕久*; 松村 大樹; 田村 和久; 西畑 保雄

表面科学, 37(2), p.78 - 83, 2016/02


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