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論文

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.

論文

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

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.

論文

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

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.

論文

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, J.*; Kim, Y.*; 福田 竜生; 吉井 賢資; 西畑 保雄; 馬場 将亮*; et al.

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

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.

論文

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

Kim, J.*; 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; et al.

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

 被引用回数:1 パーセンタイル:52.95(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.

論文

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

福島第一原子力発電所事故の教訓から、過酷事故時の環境でも原子炉建屋内の監視が可能な耐放射線性カメラシステムの開発を開始した。本研究は、カメラを構成する部品の要素技術開発を行い、カメラシステムの試作・性能を評価した。まず、要素技術開発として放射線環境下において100Gy未満で使用不能となるイメージセンサの劣化主因が暗電流増加であることを明らかにし、トランジスタの数を4つから3つに減らすとともに光電変換構造としてフォトゲート型を採用することで暗電流の軽減を図った。その結果、イメージセンサの耐放射線性は200kGy以上にまで向上した。また、光学系については、石英とフッ化カルシウムを用いた耐放射線プリズムとズームレンズにすることにより、1MGy照射後においても十分な性能を有することを示した。一方、その他の電子部品については、100kGy未満で故障するものもあり、一部に遮蔽構造を採用した。これらの結果を踏まえ、開発したカメラシステムが900kGy以上の照射線量でも良好な画像を取得できることを明らかにした。

論文

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:3 パーセンタイル:66.35(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$$_3$$.

論文

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:1 パーセンタイル:75.57(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.

論文

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

我々がプロジェクトとして取り組んできている自動車排ガスを用いた温度変化発電に関し、変換素子の材料選定等に重要となる性能指数について、素子の物理量の温度変化の測定を行うことで調べた。測定結果を用い、これまで提案されていたいくつかの性能指数の温度変化を詳しく調べて比較することで、$$F_D$$と呼ばれる指数が最も発電量との相関が高いことを示した。この指数には唯一誘電正接($$tandelta$$)が含まれており、誘電体内での電気エネルギー損失が重要であることを示唆する結果となっている。

論文

${{it In situ}}$ 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:1 パーセンタイル:87.11(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.

論文

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:7 パーセンタイル:28.11(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.

論文

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:9 パーセンタイル:32(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.

論文

耐放射線性カメラ用撮像素子の$$gamma$$線照射効果

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

東京電力福島第一原子力発電所事故の経験や教訓を踏まえ、プラント状態の情報把握能力の向上のため、耐放射線性カメラの開発に取り組んだ。放射線環境下におけるカメラ画像劣化の主因である撮像素子内の暗電流を抑制するため、撮像素子のトランジスタ及び光電変換部について3Tr型でフィールドプレートを有する素子(3TPD)、同型でフォトゲートを有する素子(3TPG)及び4Tr型でフォトゲートを有する素子(4TPG)を設計・試作し、$$gamma$$線照射中の暗電流と照射後の光電変換感度を測定した。その結果、3TPG型が最も耐放射線性が高く、200kGy照射後も十分なダイナミックレンジが維持された。

論文

アニオン形燃料電池用非白金系電極触媒の開発

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

自動車のゼロエミッション化は、環境対策技術における重要な取り組みの1つであり、そのうえで燃料電池車の開発は重要となっている。燃料電池車が普及する上で重要なのは、燃料コストが低く、インフラ整備が容易であることであり、これを満たすのは、電池材料が非貴金属で構成可能であり燃料が液体である、ヒドラジンを燃料とするアニオン形燃料電池である。我々はこのヒドラジンを燃料とするアニオン形燃料電池を開発しており、すでに2013年に試作車が完成する段階まで進んでいる。本稿では、燃料電池の心臓部である、電極触媒の開発について解説する。

論文

Imidazolium-based anion exchange membranes for alkaline anion fuel cells; Elucidation of the morphology and the interplay between the morphology and properties

Zhao, Y.; 吉村 公男; 猪谷 秀幸*; 山口 進*; 田中 裕久*; 小泉 智*; Szekely, N.*; Radulescu, A.*; Richter, D.*; 前川 康成

Soft Matter, 12(5), p.1567 - 1578, 2016/02

 被引用回数:15 パーセンタイル:14.76(Chemistry, Physical)

We investigated the interplay between morphology and properties of a new graft-type of anion exchange membranes (AEMs) containing 2-methylimidazolium groups by using contrast variation small angle neutron scattering (SANS) technique. These AEMs prepared by radiation-induced grafting of 2-methyl-1-vinylimidazole and styrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films, possessed both high alkaline durability and high conductivity. The SANS measurement reveals that these membranes are consisted of three phases: crystalline lamellar and crystallite domains originating from the pristine ETFE, which offer good mechanical properties, hydrophobic amorphous domains, which offer a matrix to create conducting regions, and interconnected hydrated domains, which are composed of the entire graft chains and water and play a key role to promote the conductivity.

論文

Novel electrothermodynamic power generation

Kim, Y.*; Kim, J.*; 山中 暁*; 中島 啓*; 小川 孝*; 芹沢 毅*; 田中 裕久*; 馬場 将亮*; 福田 竜生; 吉井 賢資; et al.

Advanced Energy Materials, 5(13), p.1401942_1 - 1401942_6, 2015/07

空中に廃棄されている自動車排ガスの廃熱の再利用は、現在社会のエネルギー問題の重要な位置を占めるが、その一つとして強誘電体(焦電体)の誘電・焦電効果を応用したエネルギー回生技術の研究が進められている。焦電体を自動車排ガス中に設置するとともに、エンジン運転に伴う熱振動に同期した電場を外部から加えることで、回生エネルギーは大幅に上昇する。本研究ではこの時用いる取り出し電気回路の改良を行うとともに、典型的な焦電体PbZr$$_x$$Ti$$_{1-x}$$O$$_3$$(PZT)を用いて実際に有効活用できる回生エネルギーが非常に小さいながらもプラスであることを初めて確認した。また回生運転と同時測定した時分割X線回折により、焦電体の結晶構造の変化やドメイン比といったミクロな機構に関する知見を得るとともに、さらに実機エンジンを用いた試験でも実際に有効活用できる回生エネルギーの取得を確認できた。

論文

電着法により創製したニッケルナノ結晶薄膜の微視構造のX線評価

田中 啓介*; 小池 裕基*; 佐野 勝基*; 田中 浩人*; 町屋 修太郎*; 菖蒲 敬久; 來海 博央*

材料, 64(7), p.528 - 535, 2015/07

スルファミン酸ニッケル浴を用いて種々の電着条件でナノ結晶ニッケルを創製し、その結晶粒径分布を、放射光を利用したX線法と透過電子顕微鏡法で計測した。その結果、(1)111-222回折ペアよりフーリエ解析で求めた粒径は、200配向膜においては、200-400ペアより求めた値より小さく、ランダム配向膜で大きくなる、(2)TEMより求めた粒径分布は対数正規分布に従い、粒径分布の分散は粒径が小さいほうが小さい、(3)111-222ペアより求めた粒径が30nm程度以下の領域では、TEMによる分布とほぼ一致する、(4)111回折を用いてシェラー法により簡便評価した粒径は111-222ペアを用いたフーリエ解析による結果に近く、粒径40nm程度以下ではTEMによる平均結晶粒径とほぼ一致する、等を明らかにした。

論文

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

坂本 友和*; 松村 大樹; 朝澤 浩一郎*; Martinez, U.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; 田村 和久; 西畑 保雄; 田中 裕久*

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

 被引用回数:28 パーセンタイル:16.33(Electrochemistry)

Carbon supported Ni, Ni$$_{0.87}$$Zn$$_{0.13}$$, and Co hydrazine electrooxidation catalysts were synthesized by an impregnation/freeze-drying procedure followed by thermal annealing for use as anode catalyst of direct hydrazine hydrate fuel cells (DHFCs). The cell performance of DHFCs changed significantly when different catalysts were used as anode. Ammonia generation from anode outlet at open circuit voltage (OCV) condition was higher for Co/C than for Ni-based catalysts. To better understand the cause of different performance and selectivity of each anode catalyst, extensive ex-situ and operando characterization was carried out. Operando XAFS measurement of Ni-K and Co-$$K$$ edge shows the potential dependence of atomic structure of Ni/C, Ni$$_{0.87}$$Zn$$_{0.13}$$/C, and Co/C during hydrazine electrooxidation reaction.

論文

Development of new type passive autocatalytic recombiner, 1; Experimental study on degradation of catalyst

上地 優; 松村 大樹; 谷口 昌司*; 西畑 保雄; 田中 裕久*; 平田 慎吾*; 原 未来也; 日野 竜太郎

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05

原子力発電所の過酷事故時においては、多量の水素が格納容器又は原子炉建屋へ放出される可能性がある。受動的触媒式再結合器(PAR)は、水素濃度緩和と安全な自己管理の最も有効な手段の一つである。既存のPARの性能向上のため、特に重量やサイズに着目した新形式のPARの開発を進めているところである。本研究では、自動車触媒の活性に対する水蒸気共存の影響について実験的な検討を実施した。その結果、水蒸気は、触媒反応の開始をわずかに遅らせる傾向があるものの、定常的な影響はないことを明らかにした。

論文

Towards optimizing the performance of self-regenerating Pt-based perovskite catalysts

Jarrige, I.*; 石井 賢司; 松村 大樹; 西畑 保雄; 吉田 雅洋*; 岸 浩史*; 谷口 昌司*; 上西 真里*; 田中 裕久*; 笠井 秀明*; et al.

ACS Catalysis, 5(2), p.1112 - 1118, 2015/02

 被引用回数:8 パーセンタイル:61.22(Chemistry, Physical)

Self-regenerating automotive catalysts owe their remarkable performance to the repeated motion of the precious metal atoms in and out of the perovskite lattice under fluctuating oxidizing and reducing conditions, preventing coalescence of the metal nanoparticles. Here we use resonant inelastic X-ray scattering to characterize the occupied and unoccupied Pt 5d states in two self-regenerating Pt-perovskite catalysts, CaTi$$_{0.95}$$Pt$$_{0.05}$$O$$_3$$ and CaZr$$_{0.95}$$Pt$$_{0.05}$$O$$_3$$. Upon reduction, the element and symmetry-specific charge excitation spectra reveal a sizeable hybridization between the Pt 5d and the Ti 3d or Zr 4d states at the interface between the nanoparticles and the perovskite, which involves the occupied states and is thus invisible in X-ray absorption spectra. A correlation is found between the strength of this d-band hybridization and the proportion of Pt nanoparticles that remain buried below the surface during reduction, indicating that the motion of the Pt atoms towards the surface is hindered by this hybridization specifically, rather than by the Pt-O bonding. These results provide direct evidence that the strength of the metal-metal d-band hybridization plays a pivotal role in determining the efficiency of self-regeneration in perovskite catalysts.

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