| HIROSHIGE MATSUMOTO | Last modified date：2024.04.02 |
Professor /
Advanced Energy Conversion Systems Thrust /
International Institute for Carbon-Neutral Energy Research
Presentations
| 1. | Kwati Leonard, Mariya E. Ivanova, Wendelin Deibert, Wilhelm A. Meulenberg, Tatsumi Ishiraha, Hiroshige Matsumoto, Processing Proton-Conducting Solid Oxide Electrolysis Cells for low Temperature Large-scale Hydrogen Production, 22nd International Conference on Solid State Ionics (SSI-22), 2019.06, Intermediate temperature (400–600 °C) steam electrolysis using ceramics proton conducting electrolytes (PC-SOECs) might offer a solution to high electrical energy consumption associated with conventional water electrolyzers through a combination of favorable thermodynamics and kinetics. This class of electrolytes is particularly favored for their relatively high ionic conductivities within this operating regime. There has been an increased interest towards PC-SOECs in recent years, aimed at reducing the cost of electrolytic hydrogen production. Although some progress has been made with small scale type PC-SOECs devices, a significant challenge has been upscaling robust and affordable planar type devices. The fabrication of such multilayered devices usually via a tape casting process requires careful control of shrinkages of individual layers to prevent warping, cracking during sintering. In this paper, 50 mm square planar cathode supported protonic electrolysis half cell consisting of Ba(Zr0.5Ce0.4)8/9Y0.2O2.9 electrolyte, NiO SrZr0.5Ce0.4Y0.1O3 δ cathode functional layer and NiO Ba(Zr0.5Ce0.4)8/9Y0.2O2.9 substrate were successfully processed using a sequential tape casting route. The smooth tri layered green tapes produced, yielded suitably dense and gas tight electrolyte after co sintering at 1350 ºC/5h. Current voltage characteristics and hydrogen evolution rates measured in the temperature range 500 600°C, using Ba0.5La0.5CoO3−δ as anode demonstrate excellent performance and durability.Electrolysis voltage as low as 1.4 V are attainable at current densities of 0.2 and 0.5 A/cm2 at 500 and 600 o C, achieving ~86 % current efficiency in the later, which is among the best PC SOECs performance reported in literature. Beside electrochemical characteristics, the morphology of the tri layered half cells were also analyzed by a combination of high angle annular dark field scanning transmission electron microscopy (HAADF STEM) with energy dispersive X ray spectroscopy (EDS).The results show substential about of Sr and Ba inter diffusion and some amount Ni migrate in the vicinity of NiO grain and the electrolyte interphase for all half cells sintered above 1450 ºC which intend results to significant ohmic losses at higher current density.. |
| 2. | Takaya Fujisaki, Aleksandar Tsekov Staykov, Yuhang Jing, Kwati Leonard, Narayana R Aluru, Hiroshige Matsumoto, Understanding the Effect of Ce and Zr on Chemical Expansion in Yttrium doped Strontium Cerate and Zirconate by Density Functional Theory and High Temperature X-Ray Analysis, 22nd International Conference on Solid State Ionics (SSI-22), 2019.06, Aliovalent cation-doped perovskite-type oxides (ABO3) exhibit proton conductivity originating from the hydration of oxide ion vacancies [1]. The hydration reaction is accompanied by structural deformation, i.e. chemical expansion. The chemical expansion may lead to mechanical failure in electrochemical devices, and thus it is necessary to understand the causes of this process at the atomic scale. In this study, the chemical expansion behaviors of Y-doped strontium cerate and zirconate were comparatively investigated. High-temperature X-ray diffraction (See Figure 1) and thermogravimetric analysis revealed that the cerate exhibits larger chemical expansion. Density functional theory calculations revealed that this tendency can be accounted for by the different atomic distribution of the Y dopant between the cerate and zirconate, which results in differences in the size of the oxide ion vacancies to be hydrated as well as different elastic character [2].. |
| 3. | Hiroshige Matsumoto, Kwati Leonard, Young-sung Lee, Issei Okuzaki, Intermediate Temperature Steam Electrolysis using BZCY and SZCY Proton Conducting Perovskites, 19th International Conference on Solid State Protonic Conductors (SSPC-19), 2018.09, [URL], Steam electrolysis is characterized by high energy conversion efficiency compared to low temperature PEM and alkaline water electrolysis, and thus is useful for hydrogen production particularly from renewable energy. Proton conducting perovskites are studied to apply to steam electrolysis for intermediate-temperature operation. We have reported so far SrZr0.5Ce0.4Y0.1O3-δ (SZCY541) and BaZr0.44Ce0.36Y0.2O3-δ (BZCY(54)8/92) to be suitable as the proton-conducting electrolytes for steam electrolysis, having both sufficient conductivity, e.g. 1.44 × 10-2 S cm-1 in wet 1 % H2 at 600°C in BZCY(54)8/92, and acceptable stability in steam at operation temperatures. In this paper, our state-of-the art steam electrolysis performance using these electrolyte materials is reported and challenges existing for their practical use is discussed. Fig. 1 shows the i-V characteristics and H2 evolution rates of a steam electrolysis experiment conducted with BZCY(54)8/92 with different thickness at 600°C. A cell terminal voltage of 1.45 V at a current density of 500 mA cm-2 with Faradaic efficiency of ~ 0.82 was obtained (T: 12 µm). From these quantities, the electric power necessary for producing 1 Nm3of H2 is calculated to be 4.2 kWh. Electronic leakage seen in Fig. 1 (b), Ohmic resistance higher than that estimated from the original conductivity, and so on are the challenges and are discussed with experimental data.. |
| 4. | Kwati Leonard, Wendelin Deibert, Mariya E. Ivanova, Wilhelm A. Meulenberg, Tatsumi Ishiraha, Hiroshige Matsumoto, Processing Ceramic Proton Conductors by Sequential Tape Casting for use in Steam Electrolysis, 19th International Conference on Solid State Protonic Conductors (SSPC-19), 2018.09, [URL], Steam electrolysis using proton conducting electrolytes (PC-SOECs) are potentially the most efficient and cost-effective option for hydrogen production at intermediate temperatures (400–600 °C) from renewable sources. These class of electrolytes are particularly favored for their relatively high ionic conductivities within this regime. Although significant progress has been made with small scale laboratory type PC-SOECs devices, a significant challenge has been upscaling robust and affordable planar type devices for comercialisation. The fabrication of such multilayered devices via a tape casting process requires careful control of shrinkages of individual layers to prevent warping, cracking or even delaminating during sintering.. |
| 5. | Issei Okuzaki1, Young Sung Lee, Kwati Leonard, Hiroshige Matsumoto, Heating-Cooling Procedure to Avoid Mechanical Failure of Proton-Conducting Ceramics, 19th International Conference on Solid State Protonic Conductors (SSPC-19), 2018.09, [URL], Hydration of oxide ion vacancy is a part of the mechanism of proton conduction to take place in aliovalent-cation-doped metal oxides but leads to chemical expansion at the critical temperature, typically 400-600°C, where the degree of hydration changes. Thus, high proton concentration that may lead to high proton conductivity will be accompanied by large chemical expansion that causes mechanical failure of the ceramic specimens. In the case of AB1-xMxO3-δ perovskite-type proton-conductors, the level of dopant M is mostly limited to 20% to the total molar amount of M and B, because highly doped specimens frequently break during preparation or conductivity measurement. In this study, we have investigated the relation between the dopant level and chemical expansion, and then a dry atmosphere or vacuum is partly introduced for the sintering and the heating-cooling during the conductivity measurement.. |
| 6. | Munemitsu Nomura, Yuki Terayama, Hiroto Eguchi, Miho Yamauchi, Yoshitsugu Sone, Omar Mendoza, Junko Matsuda, Hiroshige Matsumoto, Ionic conductivity of Protonated Layered Titanate Nano-Powder Compact in Water, 19th International Conference on Solid State Protonic Conductors (SSPC-19), 2018.09, [URL], Ion conduction in ceramic materials needs high temperature due to the necessity of thermal activation for the ionic defects to move through the crystal lattice. Analogous to the proton conduction in polyelectrolyte, the surface of hydrated metal oxide grains possibly works as proton conduction pathway with the aid of adsorbed water as conceptually shown in Fig. 1. We have reported so far high protonic conduction in Anatase nanoparticles surface-modified with sulphuric acid [1], but the sulphuric acid gradually detached on soaking with water, suggested by decreasing pH of the surrounding water. Recently, Wu et al., reported the synthesis of hydrated titania, H2Ti2O5･H2O, via a solvothermal method [2]. This work has utilized this material to investigate possible proton conduction on the surface of hydrated metal nan oxide. H2Ti2O5･H2O was prepared in the method reported in the literature [2], and spherical nano particles are obtained. XRD measurement revealed the layered structure which phase was stable up to 290°C; further increase in the temperature resulted in dehydration to deform to Anatase. The obtained powder compacted in a rectangular bar shape showed high resistance in air but the resistance markedly decreased when soaked in water: a conductivity of 7.55×10-3 s･cm-1 was obtained in water at 90°C. pH was maintained almost neutral and the conductivity seems to take place not through water. We tried to use this material for water electrolysis and evolution of hydrogen and oxygen was confirmed [3]. From these results, it is conclusive that this material has a significant ionic conduction in water or at high liquid water activity.. |
| 7. | Kwati Leonard, Vincent Thoreton, John Druce, John A. Kilner, Hiroshige Matsumoto, Characterisation of Proton Uptake through Air Electrode Materials for Electrochemical devices, Materials Challenges in Alternative and Renewable Energy (MCARE) 2018, 2018.08, [URL], Low temperature operation of solid oxide electrochemical devices such as fuel cell and electrolyzers can reduce both manufacturing and materials cost of such systems [1-3]. One approach can be the use of proton-conducting electrolytes since their activation energy for proton conduction (0.3-0.6 eV), is lower compared to oxygen-ion conducting electrolytes. In addition, such proton conducting electrolytes are very promising for steam electrolyzers to generate hydrogen, utilizing renewable energy sources [1, 3]. The vast majority of research in this area has focused on the electrolytes, with a range of materials being shown to exhibit high proton conductivity [2]. However, a key factor limiting progress in this area is the sluggish catalytic activity of the air/oxygen electrodes. For this purpose, some double perovskite oxide like BaGd0.8La0.2Co2O6−δ (BGLC) [1] has been reported to exhibit, electronic (p-type), oxygen ion and protonic conduction. In this paper, we investigate and compare the performance and cell polarization resistances of Ba0.5La0.5CoO3 (BLC) and double perovskite oxide BGLC anode on cathode supported protonic electrolysis cells using a 20μm SrZr0.5Ce0.4Y0.1O3-δ (SZCY541) electrolyte with Ni-SZCY541 composite as the H2-electrode. Also Isotope exchange experiments (18O and 2H2O tracers), Tritium imaging and Time-of-Flight Secondary Ion Mass Spectrometry depth profiling were used to study the proton uptake in the dense ceramic pellets of both materials as a means of broadening current knowledge on the availability of protons and to clarify the relationship between protons and oxide ions conduction. The BGLC 2H distribution, as inferred from the 2H216O− signal, shows an apparent depth profile which could be interpreted as 2H diffusion. Our data also suggest BGLC can indeed incorporate protons in the bulk relative to BLC at 300 ºC and that both materials retains appreciable mixed oxygen ion/electron conduction behavior. Tritium imaging plate technique however showed similar levels of protons in both materials (~5х10-8mol H/g), which are about one order of magnitude lower than that of BaZr0.44Ce0.36Y0.2O2.9 (~2,9х10-7mol H/g) at 600ºC These results will be presented together with recent work on protonic electrolysis cells. . |
| 8. | Hiroshige Matsumoto, Young-sung Lee, Mariya E. Ivanova, Kwati Leonard, Wendelin Deibert, Wilhelm A. Meulenberg, Processing Ceramic Proton conductor Membranes for Intermediate temperature Steam Electrolysis , Materials Challenges in Alternative and Renewable Energy (MCARE) 2018, 2018.08, [URL], Electrochemical devices such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are promising environmentally friendly alternative technologies for sustainable energy production. These devices generally consist of two porous electrodes separated by a dense electrolyte membrane and classified by the type of electrolyte used. Traditionally, oxide ion conducting zirconia and ceria based electrolytes have been favored for such devices, although very recently proton conducting alkaline earth cerates, zirconates and their solid solutions based electrolytes have also been attracting growing interest for lower temperature operation (600 ~ 400 °C). We have recently made significant progresses in the development of our steam electrolysis devices in two fronts. Starting from SrZr0.5Ce0.4Y0.1O3-we examined the effects of Ba substitution for Sr and the doping level of Y on the lattice structure, electrical properties, as well as chemical stability. BaZr0.44Ce0.36Y0.2O3-δ our state-of–the-art electrolyte retained a conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600°C. A cell terminal voltage of 1.45V at a current density of 500mAcm-2 with ~82 % hydrogen production efficiency was also obtained under electrolysis mode. In this presentation we will discuss some of the challenges of these proton conductors particularly for electrolysis mode of operation. On the anode side, Several transition metal containing perovskites, such as Sm0.5Sr0.5CoO3 (SSC55) can be used with acceptable electrode performance, but these materials are not sufficiently durable against high steam concentration at intermediate temperature. Another issue is the inter-diffusion of transition metal species from the electrodes to the electrolyte causing the reduction of the proton conductivity. We have examined the impact of several transition metals by introducing them as a part of the B-site component of AB0.9Y0.1O3-δ (A=Ba, Sr; B=Ce, Zr) and found that proton conductivity is more or less reduced by the transition metal incorporation. In addition, preliminary results of our recent efforts in fabricating and scaling up our protonic membrane devices by sequential tape casting will be presented. Acknowledgement This work was supported by the Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "energy carrier" (Funding agency: JST) and by World Premium International Research Center Initiative (WPI), MEXT Japan. . |
| 9. | Hiroshige Matsumoto, Young-sung Lee, Mariya E. Ivanova, Kwati Leonard, Wendelin Deibert, Wilhelm A. Meulenberg, Intermediate Temperature Steam Electrolysis using Proton Conducting perovskites membrane, 15th International Conference on Inorganic Membranes (15 ICIM 2018), 2018.06, Electrochemical devices such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are promising environmentally friendly alternative technologies for sustainable energy production. These devices generally consist of two porous electrodes separated by a dense electrolyte membrane and classified by the type of electrolyte used. Traditionally, oxide ion conducting zirconia and ceria based electrolytes have been favored for such devices, although very recently proton conducting alkaline earth cerates, zirconates and their solid solutions based electrolytes have also been attracting growing interest for lower temperature operation (600 ~ 400 °C). We have recently made significant progresses in the development of our steam electrolysis devices in two fronts. Starting from SrZr0.5Ce0.4Y0.1O3-we examined the effects of Ba substitution for Sr and the doping level of Y on the lattice structure, electrical properties, as well as chemical stability. BaZr0.44Ce0.36Y0.2O3-δ our state-of–the-art electrolyte retained a conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600°C. A cell terminal voltage of 1.45V at a current density of 500mAcm-2 with ~82 % hydrogen production efficiency was also obtained under electrolysis mode. In this presentation we will discuss some of the challenges of these proton conductors particularly for electrolysis mode of operation. On the anode side, Several transition metal containing perovskites, such as Sm0.5Sr0.5CoO3 (SSC55) can be used with acceptable electrode performance, but these materials are not sufficiently durable against high steam concentration at intermediate temperature. Another issue is the inter-diffusion of transition metal species from the electrodes to the electrolyte causing the reduction of the proton conductivity. We have examined the impact of several transition metals by introducing them as a part of the B-site component of AB0.9Y0.1O3-δ (A=Ba, Sr; B=Ce, Zr) and found that proton conductivity is more or less reduced by the transition metal incorporation. In addition, preliminary results of our recent efforts in fabricating and scaling up our protonic membrane devices by sequential tape casting will be presented.. |
| 10. | Yasuhiro Takamura, Kwati Leonard, Hiroshige Matsumoto, Effect of Dispersion of Platinum Nanoparticles in Strontium Zirconate and Strontium Cerate Proton Conductors, 233rd ECS MEETING, 2018.05, The interface of two materials having different work function leads to the development of space charge, resulting in the change of defect equivalence and hence the change in the charge carrier concentration. Another possibility lies in the formation of strain at the interface resulting in the change of the mobility of ionic charge carriers. If we can use these effects for the enhancement of ionic conductivity, introduction of hetero-interface is a potential guideline for designing new ion conduction in solids. We have reported previously that when Pt nanoparticles precipitate in proton conducting SrZr0.9Y0.1O3-δ (SZY), the electrical conductivity decreases markedly due to nanoionics effects; small amount of Pt can be dissolved into the Zr site and becomes zero-valent upon exposure to hydrogen [1]. Such a change in the macroscopic electrochemical properties is considered as a result of the unique microscopic electrochemical properties of the nanoscale space charge layer generated in the vicinity of the interface when the Pt nanoparticles are precipitated [2]. Using electrochemical spectroscopy, SrCe0.95Yb0.05O3-δ (SCYb) and Sr(Zr,Ce,Y)O3 proton conducting oxide thus doped with Pt were investigated with the aim to clarify the effects and mechanism of the Pt/oxide interface on the electrical properties of proton conducting oxide. Pt-doped proton conducting oxides were prepared by combustion synthesis method. The electrical conductivity of Pt-SZY and Pt-SCYb measured at 800 °C under 1% H2 and air atmospheres revealed a reversible nanoionics phenomenon as a result of precipitation and dissolution of platinum nanoparticles (Fig.1). The electrical conductivity then decreases significantly when the atmosphere is change to hydrogen for Pt-SZY. In the case of Pt-SCYb an increase in the conductivity can be seen for the same changes of the atmosphere. This change in electrical conductivity has been explained by the effect of precipitated Pt particles. In other words, a proton deficient region is formed in the vicinity of the interface between Pt and SZY whereas at the interface between Pt and SCYb, there is no such influence. Also, this result can be applied to deepen understanding of the reaction at the electrodes of the electrochemical cell. Comparing the electrode overvoltage when SZY and SCYb are used for the electrolyte in a cell using Pt as the electrode, SZY is several orders of magnitude larger than SCYb [3]. The reason for this can be explained if it is thought that the region where protons are not present is formed near the interface of Pt / SZY like as the case of Pt nanoparticles disperse in the bulk of SZY. On the other hand, the reason why the overvoltage at Pt/SCYb interface is smaller than that at SZY is considered to be a reasonable result of the loss of protons not taking place significantly near the interface. . |
| 11. | , [URL]. |
| 12. | , [URL]. |
| 13. | クワティ レオナルド,Vincent Thoreton,John Druce,John A. Kilner,松本広重, Characterization of Protonic Transport through Air Electrode Materials, 公益社団法人電気化学会第85回大会, 2018.03, [URL], Lowering the operation temperature of solid oxide electrolysis cells (SOECs) is an attractive concept, which avoids many of the inconveniences related to high temperature operation. Proton-conducting electrolytes (PCEs) offer some unique advantages for SOECs; one because of their low activation energy for proton motion between 400 and 600 ºC. However, there are no reported air electrode materials tailored for use with PCEs application. In the present work, Isotope exchange experiments (18O and 2D2O tracers) and Time-of-Flight Secondary Ion Mass Spectrometry depth profiling were used to study proton uptake in dense ceramic pellets of Ba0.5La0.5CoO3−δ (BGLC) and BaGd0.8La0.2Co2O6−δ (BGLC). The BGLC 2D distribution, as inferred from the 2D216O− signal, shows an apparent depth profile, which could be interpreted as 2D diffusion. Our results suggest BGLC incorporate protons in the bulk relative. We subsequently exemplify performance of both materials in in a typical steam electrolysis cell at 600°C, using SZCY541 electrolyte with Ni-SZCY541 composite as cathode.. |
| 14. | , [URL]. |
| 15. | , [URL]. |
| 16. | , [URL]. |
| 17. | KWATI LEONARD, Vincent Thoreton, John Druce, John A. Kilner, 松本 広重, Evaluation of Protonation of Air Electrode Materials and Application in Steam Electrolysis, 第43回 固体イオニクス討論会, 2017.12, Proton availability in the bulk of Ba0.5La0.5CoO3−δ (BGLC) and BaGd0.8La0.2Co2O6−δ (BGLC) has been investigated using TOF-SIMS depth profiling. The cell performance of both materials was also evaluated on cathode supported protonic electrolysis cells at 600 ºC. TOF-SIMS results show that, BGLC can incorporate protons into the bulk relative to BLC.. |
| 18. | LEE YI HSUAN, LEE YOUNGSUNG, KWATI LEONARD, Hiroshige Matsumoto, Effect of transition metal on BZCY-based protonic conductor, INTERNATIONAL WORKSHOP PROSPECTS ON PROTONIC CERAMIC CELLS (PPCC-2017), 2017.10, Proton conductor has been regarded as electrolyte materials for solid oxide fuel cells (SOFC) and electrolysers (SOEC). Given that proton conductor could reduce operating temperature for SOFC/SOEC system, this system will extend wildly applications. Oxides containing transition metals are commonly utilized as electrodes. During preparation and operation process, transition metals would diffuse from anode or cathode to the electrolyte. These phenomena caused to degrade the electrolyte conductivity. Shimura et al. shows significant decrease in the conductivity of BaCe0.9Y0.1O3-δ-based proton conductors when partial replacement of Fe, Mn and Co for Ce [1]. In addition, Leonard et al. reported that Ba(Zr0.5Ce0.4)0.8Y0.2O3-δ (BZCY542) has a high proton mobility and chemical stability [2]. The BCZY542 could be considered as a suitable electrolyte material for SOFC/SOEC. In this study, therefore, the transition metal doping BZCY542-based materials were fabricated, i.e., Ba(Zr0.5Ce0.4)0.75Y0.2M0.05O3-δ (M = Co, Fe and Ni), and the effect of transition metals were investigated on their electrical conduction properties. BZCY542-based materials were prepared by a chemical solution method. Phase identification was carried out by X-ray diffraction. The conductivity was measured by a four-terminal AC impedance method. Figure 1 shows that the introduction of transition metals resulted in the reduction conductivity of the BZCY-based materials under air and H2 atmosphere. Furthermore, the conductivity tendency of BZCYNi, comparing with BZCYCo and BZCYFe, changed more significantly in 1% H2 atmosphere than in air atmosphere. It is suggested that the difference between in air and in H2 condition may result from the tendency to absorb O-H and the change of proton transport number. . |
| 19. | 藤崎 貴也, 髙村 泰宏 , Alexander Staykov, 松本 広重, Theoretical Study for the Effect of Pt Nanoparticles on the Proton Conducting Properties of Strontium Cerate and Zirconate, トークシャワー・イン・九州2017, 2017.09, ペロブスカイト構造を有するプロトン伝導性酸化物(一般式：AB1-xMxO3-δ)は、水蒸気雰囲気において400℃から800℃程度の温度でプロトン伝導性を発現する。近年、Ptを固溶させたプロトン伝導体の一種であるSrZr0.9Y0.1O3-δは、水素中でPtナノ粒子が析出し電気伝導率が下がることが報告された。一方、Ptを固溶させたSrCe0.95Yb0.05O3-δは、水素中で同様にPtナノ粒子が析出し、電気伝導率が上がることが報告された[1]。本研究は、上記の二つの現象が析出したPtナノ粒子とプロトン伝導性酸化物のヘテロ界面において、電荷の移動が起こり互いの欠陥平衡に影響を及ぼした可能性を挙げ、第一原理計算により調査を行った。. |
| 20. | 藤崎 貴也 , Alexander Staykov, 高村 泰宏, 松本 広重, Theoretical Study for the Effect of Pt Nanoparticles on the Proton Conducting Properties of Strontium Cerate and Zirconate, 第13回 固体イオニクスセミナー, 2017.09, ペロブスカイト構造を有するプロトン伝導性酸化物(一般式：AB1-xMxO3-δ)は、水蒸気雰囲気において400℃から800℃程度の温度でプロトン伝導性を発現する。近年、Ptを固溶させたプロトン伝導体の一種であるSrZr0.9Y0.1O3-δは、水素中でPtナノ粒子が析出し電気伝導率が下がることが報告された。一方、Ptを固溶させたSrCe0.95Yb0.05O3-δは、水素中で同様にPtナノ粒子が析出し、電気伝導率が上がることが報告された[1]。本研究は、上記の二つの現象が析出したPtナノ粒子とプロトン伝導性酸化物のヘテロ界面において、電荷の移動が起こり互いの欠陥平衡に影響を及ぼした可能性を挙げ、第一原理計算により調査を行った。. |
| 21. | KWATI LEONARD, John Druce, Vincent Thoreton, John A. Kilner, 松本 広重, Mixed Proton-Electron Conducting Air Electrode for Protonic Steam Electrolysis Cells, 第13回 固体イオニクスセミナー, 2017.09, Proton conducting electrolytes (PC) are promising intermediate temperature alternative to oxide ion conducting electrolytes (OC) in electrolysis and solid oxide fuel cells. Interest in PC stems from their high conductivity and low migration energy barriers which are usually within the range [1, 3]. A major concern with intermediate temperature operation is the sluggish kinetics, as well as high polarization resistance of the steam electrode materials particularly at high current densities. Mixed proton/electron conductor (P-MIECs) materials with protonic conductivity exceeding 10-5-10-4 to initiate a bulk transport path can significantly alleviate such drawbacks, since the reactive zone within such materials can be extended well beyond the gas/electrode/electrolyte triple phase boundary [1]. In this work, cathode supported protonic electrolysis cells using a 25μm SrZr0.5Ce0.4Y0.1O3-δ electrolyte with Ni-SZCY541 composite as the H2-electrode and double perovskite oxide BaGd0.8La0.2Co2O6−δ (BGLC) as the anode was investigated. The oxygen and proton transport properties through the bulk and across the gas electrolyte interfaces of BGLC was also studied by direct measurement of the tracer diffusions and surface exchange coefficients using a combination of stable isotope exchange experiments (18O and 2D2O tracers) and Time-of-Flight Secondary Ion Mass Spectrometry depth profiling.. |
| 22. | Hiroshige Matsumoto, KWATI LEONARD, Young-Sung Lee, Kuninori Miyazaki, Yuji Okuyama, Intermediate-Temperature Steam Electrolysis Using Proton-Conducting Perovskite for Hydrogen Production, IUMRS-ICAM 2017, 2017.09. |
| 23. | Hiroshige Matsumoto, Proton-Conductor Steam Electrolysis Cell for Hydrogen Production, 中国材料学会2017, 2017.07, [URL], Water electrolysis is an important technology for producing renewable hydrogen and work for energy conversion between the electricity and hydrogen in combination with hydrogen fuel cells. Steam electrolysis is characterized by low electrolysis voltage in comparison with other methods, but the drawback is high operation temperature. Proton conduction in metal oxides is less temperature-dependent than oxide ion conduction in zirconia, and this aspect enables us to operate steam electrolysis at intermediate temperatures. This paper demonstrates conductivity and stability of some perovskite-type proton conducting metal oxides and the intermediate temperature operation of steam electrolysis. We also discuss several challenges of the proton conductor cells particularly for the electrolysis mode of operation. . |
| 24. | KWATI LEONARD, John Druce, Vincent Thoreton, John A. Kilner, Hiroshige Matsumoto, Exploring Mixed Proton/Electron Conducting Air Electrode materials in Protonic Electrolysis Cells, 21st International Conference on Solid Stare Ionics, 2017.06, Ceramic proton conducting electrolytes are promising intermediate temperature alternative to oxide ion conducting electrolytes in steam electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). This stems from their lower activation energy for H+ motion and ability to produce fairly pure H2 at the cathode side wheras tradition oxide ion conducting electrolytes leave wet H2 at the steam side when operated in electrolysis mode. A major concern with intemediate temperation operation is the sluggish kinetics, as well as high polarization resistance of the steam electrode materials particularly at high current densities and low faradaic efficiencies. Mixed proton/electron conductor (P-MIECs) materials with protonic conductivity exceeding 10-5-10-4 to initiat a bulk transport path can significantly alliviate such drawbacks, since the reactive zone within such materials can be extended well beyond the gas/electrode/electrolyte triple phase boundary. Very recently Ba0.5Sr0.5Fe0.8Zn0.2O3-δ (BSFZ) [1] and double perovskite oxide BaGd0.8La0.2Co2O6−δ (BGLC) [2] were proposed as possible mixed proton/electron conductors (P-MIECs) on acount of their considerable protonation between 300–400 °C. Although these materials works effectively on proton conducting electrolytes very few studies have probe the specific ionic carriers responsible for transport within the bulk of such materials. In the present contribution, cathode-supported protonic electrolysis cells using a 25μm SrZr0.5Ce0.4Y0.1O3-δ electrolyte [3] with Ni-SZCY composite as the H2-electrode and BGLC as the anode was investigated. The assembled cells was tested with humidified 1%O2 (∼80% H2O) fed in at the steam electrode and 1%H2-99% Ar at the H2-electrode. The area specific resistance associated with the steam electrode polarization process between 500~700 °C was also measured by AC impedance spectroscopy whereas the voltage drop across the cells was measured by current interrupt method. The oxygen and proton transport properties through the bulk and across the gas electrolyte interfaces of BGLC was also studied by direct measurement of the tracer diffusions and surface exchange coefficients using a combination of stable isotope exchange experiments (18O and 2D2O tracers) and Time-of-Flight Secondary Ion Mass Spectrometry depth profiling (ToF-SIMS). This paper discusses these aspects as well as the interaction between P-MIECs electrode kinetics, total cell voltage, hydrogen generation efficiency and their implication on protonic steam electrolysis cells.. |
| 25. | Yasuhiro Takamura, Hiroshige Matsumoto, KWATI LEONARD, Novel Functionality of Proton Conducting Perovskites Type Oxides Utilizing Nanoionics Effect, 21st International Conference on Solid Stare Ionics, 2017.06, We have reported previously that when nano-sized Pt particles precipitate in proton conducting SrZr0.9Y0.1O3-δ (SZY), the electrical conductivity decreases markedly due to nanoionics effects [1]. Such a change in the macroscopic electrochemical properties is considered as a result of the unique microscopic electrochemical properties of the nanoscale space charge layer generated in the vicinity of the interface when the Pt nanoparticles are precipitated [2]. Using electrochemical spectroscopy, Pt doped SrCe0.95Yb0.05O3-δ (SCYb) and Sr(Zr,Ce,Y)O3 proton conducting oxide were investigated with the aim to clarify the effects and mechanism of the Pt / oxide interface on the electrical properties of protonic conducting oxide. Furthermore, the voltage drop at the electrode / electrolyte interface in electrochemical cells comprising Pt/ Sr(Zr,Ce,Y)O3/Pt were also measured using current interruption method in order to adequately compare and contrast these effects on proton conducting oxide. Based on the obtained knowledge, we aim to construct a novel electrode / electrolyte having excellent functionality. Pt-doped proton conductivity oxides were prepared by combustion synthesis method. The electrical conductivity of Pt-SZY and Pt-SCYb measured at 800°C under 1% H2 and air atmospheres revealed a reversible nanoionics phenomenon as a result of precipitation and dissolution of platinum nanoparticles. The electrical conductivity then decreases significantly when the atmosphere is change to hydrogen for Pt-SZY. In the case of Pt-SCYb an increase in the conductivity can be seen for the same changes of the atmosphere. This change in electrical conductivity has been explained by the effect of precipitated Pt particles. In addition, from the current interruption method using Pt as the electrode on SZY and SCYb electrolyte, the electrode overvoltage significantly increases after applying a small current on Pt/SZY/Pt cell. On the other hand the electrode overvoltage drops when SCYb electrolyte is used in the same system. This indicates that a high resistance layer is formed at the Pt/SZY interface, which is related to the decrease of the electrical conductivity under 1% H2 in the four prove method. In my presentation, we discuss these results together with the electrochemical characteristics of the Pt/oxide interface with proton conductive oxide.. |
| 26. | KWATI LEONARD, Lee Young-Sung, Hiroshige Matsumoto, Degradation Behavior in Steam Electrolysis Cells Using SZr0.5Ce0.4Y0.1O3-δ Proton conducting electrolyte, 電気化学会第84回大会, 2017.03. |
| 27. | Hiroshige Matsumoto, Young-Sung Lee, KWATI LEONARD, Yuji Okuyama, Influence of transition metal inter diffusion on proton-conductivity and electrode activity of perovskites , The 8th German-Italian-Japanese Meeting of Electrochemists, 2016.12, Proton-conducting electrolytes are an important and indispensable component of fuel cells and electrolyzers, governing the performance and to a large extent the design of the system. Oxides containing transition metals are commonly used as electrodes. During preparation and operation of the fuel cells, transition metals will diffuse from the electrodes to the electrolyte. A possible concern is that the diffusion of these transition metals will degrade the electrical conductivity of the electrolyte. There is a concern that the diffused transition metals will degrade the electrolyte conductivity. Shimura et al. reported significant decrease in the conductivity of BaCe0.9Y0.1O3-δ-based proton conductors on replacing partially Fe, Mn and Co for Ce [1]. In this study, the transition metal doping has been performed, i.e., AB0.9-xY0.1MxO3-δ (A = Ba and Sr, B = Zr and Ce, M = Co, Fe, Ni and Mn), and their electrical conduction and transport number properties were investigated to examine the effect of introducing transition metals to the proton conductor oxides. The electrical conductivity and transport number change was observed by introducing transition metals. Especially, Ni-doped SCY and BCY were slightly changed than the un-doped original electrolytes. However, it has almost half of proton transport number at 600 oC in H2 atmosphere. These results suggest that the transition metal doping do cause changes in the ionic conductivity of the electrolytes from that of the original proton conductor and that the magnitude of the conductivity change depends on the transition metals and parent proton conductors.. |
| 28. | KWATI LEONARD, Young-Sung Lee, Yuji Okuyama, Kuninori Miyazaki, Hiroshige Matsumoto, Proton Conducting Perovskites For Hydrogen Production Via Steam Electrolysis, The 8th German-Italian-Japanese Meeting of Electrochemists, 2016.12, In this contribution, we present our resent findings on conductivity and stability of some perovskite-type proton conducting metal oxides and their application in steam electrolyzers cells at intermediate temperature. Starting from SrZr0.5Ce0.4Y0.1O3-δ (SZCY541), we examined the effects of Ba substitution for Sr and the doping level of Y on the lattice structure, electrical properties, as well as the proton content of the following compositions A(Zr5/9Ce4/9)1-xYxO3-δ, (A= Ba, Sr and x=0.1, 0.2). Cell terminal voltages, examined for thin film of (SZCY541) electrolyte on Ni-SZCY541 cathode substrates with Sr0.5Sm0.5CoO3 (SSC55) as anode gave a current density of 0.5 A cm-2 at an applied electrolysis voltage of 2 V. Whereas thin film of BZCY electrolyte gave a much improved performance at the same current density. On the electrode side, we show that some of the widely use electrode materials with acceptable electrode performance like SSC55 are not sufficiently durable against high steam concentration at 600 °C. Another issue is the inter-diffusion of transition metal species from the electrodes to the electrolyte causing the reduction of the proton conductivity.. |
| 29. | Yasuhiro Takamura, KWATI LEONARD, Hiroshige Matsumoto, Effect of hetero-interfaces introduced dispersion of platinum nanoparticles on the proton-conducting properties of strontium cerate and zirconate, The 8th German-Italian-Japanese Meeting of Electrochemists, 2016.12, Ionic properties of metal oxides possibly changes in the vicinity of the interface with a hetero-phase material due to the formation of space charge layer and/or the strain originated from different coefficients of thermal expansion between the two materials, followed by the rearrangement of charge carriers [1]. In particular, the former case can be examined in a material with well dispersed second phase particles as an intriguing approach to alter the macroscopic properties [2]. This so-called nanoionics composite materials can be applied in energy conversion devices. In this work, we have examined and clarified the effects of homogeneously dispersed platinum nanoparticles on the proton conducting oxides.. |
| 30. | KWATI LEONARD, Young-Sung Lee, Hiroshige Matsumoto, Proton Conducting Perovskites and Application to Hydrogen Production via Steam Electrolysis , EEMAS 2016, 2016.11, In the present contribution, we demonstrates our resent results on conductivity and stability of some perovskite-type proton conducting metal oxides and their application in steam electrolyzers cells at intermediate temperature. Starting from SrZr0.5Ce0.4Y0.1O3-δ (SZCY541), we examined the effects of Ba substitution for Sr and the doping level of Y on the lattice structure, electrical properties, as well as the proton content of the following compositions A(Zr5/9Ce4/9)1-xYxO3-δ, (A= Ba, Sr and x=0.1, 0.2). Cell terminal voltages, examined for thin film of (SZCY541) electrolyte on Ni-SZCY541 cathode substrates with Sr0.5Sm0.5CoO3 (SSC55) as anode gave a current density of 0.5 A cm-2 at an applied electrolysis voltage of 2 V. Whereas thin film of BZCY electrolyte gave a much improved performance at the same current density. On the electrode side, we show that some of the widely use electrode materials with acceptable electrode performance like SSC55 are not sufficiently durable against high steam concentration at 600 °C. Another issue is the inter-diffusion of transition metal species from the electrodes to the electrolyte causing the reduction of the proton conductivity. . |
| 31. | Yasuhiro Takamura, KWATI LEONARD, Hiroshige Matsumoto, Effect of dispersion of platinum nanoparticles on the proton-conducting properties of strontium cerate and zirconate, PRiME 2016, 2016.10, [URL], Nanoionics phenomenon in a Pt-containing proton-conducting oxide (Pt-r0.9Y0.1O3−α) was demonstrated. . |
| 32. | Young-sung Lee, KWATI LEONARD, Yuji Okuyama, Hiroshige Matsumoto, A study of transition metal doping on the electrical properties of perovskite type proton conductor, PRiME 2016, 2016.10, [URL], Proton-conducting oxides have been studied as intermediate-temperature electrolyte materials for fuel cells and steam electrolysis. . |
| 33. | Shota Maeda, Daisuke Kurashina, KWATI LEONARD, Young-sung Lee, Hiroshige Matsumoto, Electrochemical methane reforming using SrZr0.5Ce0.4Y0.1O3-δ proton-conductor cell , PRiME 2016, 2016.10, [URL], In this study, we examined the device for separating only hydrogen by steam eforming of methane using a proton conductor cell. . |
| 34. | KWATI LEONARD, Young-sung Lee, Yuji Okuyama, Kuninori Miyazaki, Hiroshige Matsumoto, Proton Conduction Properties of BZCY and SZCY Perovskites Type Oxides; Addressing the Effect of Dopant Levels and Proton Content , PRiME 2016, 2016.10, [URL], Chemically Stable proton conducting BZCY(54)8/9-2 has been developed as a promising proton conducting electrolytes for intermediate temperature BZCY(54)8/9-2 retained a high proton conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600° C as well as sufficient chemical stability under 80 % steam for 200 hours. Steam electrolysis using SZCY541 and as electrolytes was also investigated. BZCY(54)8/9-2 was most effective in reducing the cell over potential in the examined devices.. |
| 35. | Yuki Terayama, Takamasa Haji, Kouhei Mori, Hiroshige Matsumoto, Water Electrolysis Using Water Absorbing Porous Electrolyte Cell, PRiME 2016, 2016.10, [URL], We have developed water electrolysis cell by use of a water absorbing porous electrolyte that works under similar conditions to a polymer electrolyte electrolysis cell. This cell consist of a surface-proton conducting metal oxide nanoparticles as proton-conducting electrolyte, a controlled-hydrophobic electrocatalytic layer, and fully hydrophobic gas diffusion layer. In this presentation, we will show that the hydrogen gas generation rate depend on the supplied water pressure by water electrolysis.. |
| 36. | Hiroshige Matsumoto, KWATI LEONARD, Young-sung Lee, Yuji Okuyama, Kuninori Miyazaki, Steam Electrolysis Using Proton-Conducting Perovskite, PRiME 2016, 2016.10, [URL], Steam electrolysis using proton-conducting electrolyte is reviewed. Present status and challenges including the issue of electronic leakage and transition metal diffusion between electrode and electrolyte are presented.. |
| 37. | KWATI LEONARD, Young-Sung Lee, Yuji Okuyama, Hiroshige Matsumoto, Transport Properties of BZCY and SZCY Proton Conducting Perovskites For Hydrogen Production, 第１２回 固体イオニクスセミナー, 2016.09, Dense protonic electrolytes materials with the formula A(Zr5/9Ce4/9)1-xYxO3-δ, (A= Ba, Sr and x=0.1, 0.2) were obtained via chemical solution approach BZCY(54)8/92 showed a maximum proton occupancy of 17.1 mol % at 100 °C and retained the highest protonic conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600 °C as well as sufficient stability under 80 % steam. Proton occupancy is the major driving force for the high conductivity in the materials.. |
| 38. | KWATI LEONARD, Young-Sung Lee, Yuji Okuyama, Kuninori Miyazaki, Hiroshige Matsumoto, Transport Properties of BZCY and SZCY Proton Conducting Perovskites: Implication of Different Electrode Materials on the Impedance spectra, SSPC-18, 2016.09, dense yttrium doped solid solutions of barium cerate, strontium cerate and zirconate with the formula A(Zr5/9Ce4/9)1-xYxO3-δ, (A= Ba, Sr and x=0.1, 0.2) were prepared and studied as potential proton conducting electrolytes for intermediate temperature peration. The transport properties of the sintered pellets were examined by AC impedance spectroscopy using porous platinum, silver and silver palladium paste as electrode respectively. The de-convoluted bulk, and grain boundary conductivity from the respective electrodes were obtained and compared. The bulk and grain boundary contributions were easily discernable in the impedance spectra of the studied compositions when porous platinum is used as electrode relative to silver electrode.. |
| 39. | Takaya Fujisaki, KWATI LEONARD, Young-Sung Lee, Yuji Zenitani, Hiroshige Matsumoto, Electrical Conduction Behavior of Yttrium-Doped Strontium Zirconate in Dry Hydrogen Gas , SSPC-18, 2016.09, ある種の金属酸化物であるプロトン伝導体は固体酸化物燃料電池の電解質に応用が期待されている。プロトン伝導は酸素空孔に水が水和した結果として理解されている。今回、それを高温と乾燥水素に曝したところ、これまで観測されたことの無い電気伝導度が得られた。その電気伝導度が得られた条件を模した、水素濃淡電池による起電力測定により、同一方向の起電力が観測された。この起電力から、伝導種は水素が供給したプロトンの可能性が示唆された。. |
| 40. | Hiroshige Matsumoto, Young-Sung Lee, KWATI LEONARD, Yuji Okuyama, A study of the ionic properties in (Ba,Sr)(Ce,Zr)0.9Y0.1O3-δ proton conducting perovskite type oxide, SSPC-18, 2016.09, プロトン伝導性酸化物に遷移金属が固溶したときの影響を調べた。遷移金属の固溶により、多くの場合にプロトン伝導性が低下した。電気化学セルを構成した場合に、電解質抵抗だけでなく電極反応にも影響を及ぼした。. |
| 41. | KWATI LEONARD, Young-Sung Lee, Takamura Yasuhiro, Hiroshige Matsumoto, Nanoionics Effects of Disperse Platinum Particles on SrCeO3 and SrZrO3 based proton conductors, Rare Earth 2016 in SAPPORO, JAPAN, 2016.06. |
| 42. | Takaya Fujisaki, KWATI LEONARD, Young-Sung Lee, Yuji Zenitani, Hiroshige Matsumoto, Electrical Conduction Behavior of Yttrium-Doped Strontium Zirconate in Dry Hydrogen Gas, Rare Earth 2016 in SAPPORO, JAPAN, 2016.06, It is essential for hydration reaction in proton conductor to introduce water molecule. At present, unexpected conductivity with proton conductor was observed in dry hydrogen. It seems that this proton conductor had proton conduction in the atmosphere.. |
| 43. | Hiroshige Matsumoto, Yuki Terayama, Takamasa Haji, Kouhei Mori, Water-Absorbing Porous Electrolyte Cell for Water Electrolysis, EMN Meeting on Fuel Cells, 2016.05, A “water-absorbing porous electrolyte cell” is proposed and demonstrated as a method of water electrolysis that will play an important role for the production of renewable hydrogen. Materials and the water electrolysis characteristics is reported.. |
| 44. | KWATI LEONARD, Hiroshige Matsumoto, PROTON CONDUCTORS BASED SOLID OXIDE ELECTROLYSIS CELLS, I²CNER / EnMaCh Joint International Symposium, 2016.02. |
| 45. | Yuki Terayama, Hiroshige Matsumoto, Water Electrolysis using Water-Absorbing Porous Electrolyte Cell, I2CNER Annual Symposium 2016, 2016.02, [URL], Water-absorbing porous electrolyte cell consists of a surface-proton conducting metal oxide nanoparticles, controlled-hydrophobic catalytic layers and fully hydrophobic and gas diffusion layers. (1) electrolyte, (2) gas diffusion layer, and (3) electrode parts of the cell are the research subjects, so that the investigations are also contributing to Project 1 Electrodes and Project 2 Electrolyte.. |
| 46. | KWATI LEONARD, Hiroshige Matsumoto, DEVELOPMENT OF PROTON CONDUCTOR BASED SOLID OXIDE ELECTROLYSIS CELLS , I2CNER Annual Symposium 2016, 2016.02, [URL], Design and synthesize highly durable compactible electrode materials and the fabrication of ultra-thin electrolytes (≤ 20μm) materials using microfabrication techniques for advance SPECs and SPFCs devices Convenient production of dry and fairly pure hydrogen without additional gas separation systems, in comparison to oxygen ionic conductor . |
| 47. | レオナルド クワティ, イ ヨンソン, 高村泰宏, 松本 広重, SrCeO3系および SrZrO3系プロトン伝導体への白金ナノ粒子分散による ナノイオニクス効果, 第 41 回固体イオニクス討論会, 2015.11, The present work demonstrates nanoionics effects using SrCe0.95Yb0.05O3−δ. and SrZr0.9Y0.1O3−δ as the major matrix phases and platinum metal nanoparticles as the minor dispersed phase. The platinum phase was introduced via the combustion synthesis approach and sintered at 1100 o C, resulting in solid solutions with platinum in the perovskite lattice. A reversible nanoionics phenomenon is observed under reducing and oxidizing atmospheres as a result of platinum nanoparticles precipitation.. |
| 48. | Hiroshige Matsumoto, Seok-Jun Kim, Osamu Fujiwara, Yuki Terayama, KWATI LEONARD, Young-Sung Lee, Water-Absorbing Porous Electrolyte Cell for Water Electrolysis Using SurfaceProton-Conducting Nanoparticles, WHTC2015, 2015.10, Hydrogen is considered as a secondary energy and can be used as an energy carier to help address concerns about energy security and global climate change. Hydrogen can be carbon-neutral when it is produced from renewable energies, such as solar and wind energy. Water electrolysis is a means to convert electricity to hydrogen. There are several types of water electrolysis with both merit and demerit. In this paper, a “water-absorbing porous electrolyte cell” (Fig. 1 a) is propsed and demonstrated as a method of water electrolysis. Materials and the water electrolysis characteristics are introduced and discussed. Proton conduction on an acid-modified surface metal oxide nanoparticles is employed as the electrolyte (Fig. 1 b). The interior portion of the particles is insulating whereas the surface is utilized as a proton conduction pathway (Fig. 1 c). Particle size reduction resulted in a high surface area and hence a large proton conducting surface. The authors have found so far that sulfonated titania nanoparticles prepaired via thermal decomposition of titanyl sulfate show high proton conduction in both water and humid atmosphere [1].. |
| 49. | Hiroshige Matsumoto, KWATI LEONARD, Young-Sung Lee, Yuji Okuyama, Influence of Dopant Levels on the Proton-Conducting Properties of ZCY and BZCY system, Materials Science and Technology 2015 (MS&T15), 2015.10, Y-doped A(Zr,Ce)O3, at Zr/Ce=5/4 with A being either Ba or r has been studied as a potential proton conducting electrolyte. The effects of Ba substitution for r and Y doping level on the lattice structure, proton content, electrical properties, hydration behavior, as well as chemical stability are investigated. Thermo-gravimetric analyses revealed a similar proton concentration in both 10％ and 20% Y doping cases for A=r, resulting in almost comparable proton conductivities in both wet hydrogen and oxygen atmosphere. When A=Ba, Y doping level of 20% results in higher conductivity than the 10% Y doped case. These results suggest that Ba and r at A-site have different effects on hydration and proton mobility.. |
| 50. | Leonard Kwati, Young Sun Lee, Yasuhiro Takamura, Hiroshige Matsumoto, Effects of Pt Nanoparticles Dispersion on SrCeO3 and SrZrO3 based proton conductors, 2015年電気化学秋季大会, 2015.09. |
| 51. | Takaya Fujisaki, KWATI LEONARD, Young Sung Lee, Yuji Zenitani, Hiroshige Matsumoto, Novel Electrical Conduction Observed in Yttrium-Doped Strontium Zirconate in Dry Hydrogen , PPCC 2015 , 2015.07, A solid oxide fuel cell (SOFC) is an electrochemical energy conversion device that directly converts the chemical energy of fuel to electricity with high energy efficiency [1]. SOFC consists of two porous electrodes (cathode and anode) and a dense electrolyte. The performance of the device depends on the efficient movement of protons within it. Proton conductivity has been reported for many perovskites type oxides (ABO3) when doped with an aliovalent element in the B site and exposure in a humidified atmosphere. The humidified atmosphere is essential for the hydration process which ultimately provides the protons in the electrolyte [2]. In the present study we report an unpreceded conductivity of SrZr0.9Y0.1O3-δ(SZY91) electrolyte after exposure to dry hydrogen gas. The high conductivity is not explicable from conventional proton and electron conduction mechanism [3]. Therefore, a conduction mechanism observed is not well understood at this time. SZY91 which is replaced zirconium with yttrium by 10% compared to SrZO3 was prepared by a solid-state reaction method. Upon exposure to dry hydrogen gas at 900 oC the observed conductivity is as shown in figure 1. This figure indicates results of conductivity at different temperatures during heating and cooling in dry hydrogen gas. According to these results,novel proton conduction may be the reason for the change in conduction. . |
| 52. | Young Sung Lee, KWATI LEONARD, Yuji Okuyama, Hiroshige Matsumoto, Effect of transition metal doping on the electrical properties of alkali earth cerates and zirconates , PPCC 2015 , 2015.07, Proton conductor can be used as electrolytes for fuel cells and electrolyzers. Solid electrolytes are the most important and indispensable component of fuel cells and electrolyzers, governing the performance and to a large extent the design of the system. Oxides containing transition metals are commonly used as electrodes. During preparation and operation of the fuel cells, transition metals will diffuse from the electrodes to the electrolyte. There is a concern that the diffused transition metals will degrade the electrolyte conductivity. Shimura et al. reported significant decrease in the conductivity of BaCe0.9Y0.1O3-δ-based proton conductors on replacing partially Fe, Mn and Co for Ce [1]. In this study, the transition metal doping has been performed, i.e., AB0.9-xY0.1MxO3-δ (A = Ba and Sr, B = Zr and Ce, M = Co, Fe, Ni and Mn), and their electrical conduction properties were investigated to examine the effect of introducing transition metals to the proton conductor oxides. AB0.9-xY0.1MxO3-δ (SZYM, SCYM, BCYM and BZYM) were prepared by a solid-state reaction method. Phase identification was carried out by X-ray diffraction. The conductivity was measured by a four-terminal AC impedance method. The electrical conductivity change was observed by introducing transition metals. These results suggest that the introduction of transition metals causes the change in the conductivity of the proton conducting electrolytes in most cases, and that the change in the conductivity depends on the sort of transition metals. This means that the impact of introducing transition metals to the electrical conduction properties depends on the oxide. The above two cases suggests that either A-site (Sr or Ba) or B-site (Ce or Zr) possibly governs for the impact of conductivity is sensitive to the transition metals. . |
| 53. | Kuninori Miyazaki, Shinya Kitaguchi, Masatoshi Ikeda, Hayahide Yamasaki, Hiroshige Matsumoto, Research of Intermediate Temperature Steam Electrolysis Cells Using Proton-conducting Oxide Electrolyte, 第４回JACI/GSCシンポジウム＆第７回GSC東京国際会議, 2015.07, [URL]. |
| 54. | Young Sung Lee, KWATI LEONARD, Yuji Okuyama, Hiroshige Matsumoto, The effect of transition metals doping on the electrical properties of perovskite type proton conductor, 日本化学会九州支部設立100周年記念国際シンポジウム 第５２回化学関連支部合同九州大会, 2015.06, The effect of the presence of transition metal at the B site of the proton conducting perovskites type oxide has been investigated. AB0.85Y0.1MxO3-δ (A=Ba, Sr, B=Ce, Zr, M = Co, Fe, Ni, Mn) was prepared and their electrochemical behavior in oxidative and reducing atmospheres examined. The electrical conductivity varies, decreasing in most cases, upon the introduction of the transition metals and the changes take place in different ways depending on A-site or B-site as well as the atmospheres.. |
| 55. | KWATI LEONARD, Young Sung Lee, Takaya Fujisaki, Yuji Okuyama, Hiroshige Matsumoto, Nanoionic Effects on the Proton Conductivity of Cerates and Zirconates Based Perovskites-type Oxides, 日本化学会九州支部設立100周年記念国際シンポジウム 第５２回化学関連支部合同九州大会, 2015.06, The present work, we demonstrate nanoionics effects using SrCe0.95Yb0.05O3−α. and SrZr0.9Y0.1O3−α as the major matrix phase and platinum metal nanoparticles as the minor dispersed phase. A reversible nanoionics phenomenon is observed under reducing and oxidizing atmospheres as a result of platinum nanoparticles precipitation.. |
| 56. | Hiroshige Matsumoto, Osamu Fujiwara, KWATI LEONARD, Young-Sung Lee, Surface-Proton Conductivity of Titanium Phosphate Nanoparticles in Water, 20th International Conference on Solid State Ionics, 2015.06, [URL], Proton conductivity of Ti-P-O complex oxide nanoparticles in water has been investigated, assuming the use as an electrolyte material for water electrolysis. Most of the solid ion conductor is crystalline and ionic defects works as charge carriers, so that relatively high temperature is necessary for the ionic conduction. Surface of the solid can work another type of the ion conduction field and nanoparticles equipped with large surface area can be ion conduction media, with examples of ceria nanoparticles and acid-modified metal oxides. In this work proton incorporated on the surface of Ti-P oxide nanoparticles in the form of hydroxyl group is assumed as a charge carrier and its conductivity with a help of liquid water is considered. The Ti-P oxide particles were prepared via a wet chemical method using titanium alkoxide and phosphoric acid. Resulting precipitates are washed dried and compacted in a disk or bar shape and electrical conductivity in water was measured. Dissolution of phosphoric acid into water was evaluated by measuring the pH. The conductivity and the dissolution tendency depends largely on the heat treatment and the ratip of Ti/P. Infrared absorption measurement reveals the P=O double bond and Ti-O-P bond, with existence of OH group part of which can be assumed to work as a source of protonic charge carrier. . |
| 57. | KWATI LEONARD, Yuji Okuyama, Young-Sung Lee, Hiroshige Matsumoto, The Influence of Dopant Levels on the Hydration Properties of SZCY and BZCY Proton Conducting Ceramics for Hydrogen Production, 20th International Conference on Solid State Ionics, 2015.06, [URL], Ionic conductivity is an important transport process for all electrochemical energy conversion and storage devices and very relevant for a sustainable energy economy. In the present work Yttria-doped strontium zirconate partially substitted with ceria SrZr0.5Ce0.4Y0.1O3-α (SZCY541) have been studied as a potential proton conducting electrolyte for intermediate temperature steam electrolysis. The effects of Ba substitution for Sr on the lattice structure, proton content, electrical properties, hydration behavior, as well as chemical stability are investigated. Proton content was examined by tailoring dopant concentration to improve the proton conductivity. Thermo-gravimetric analyses revealed a similar proton concentration in both SZCY541 and SrZr0.44Ce0.35Y0.2O3-α (SZCY542) with a constant Zr/Ce fraction of 5:4. Both samples showed almost comparable proton conductivities in both wet hydrogen and oxygen atmosphere. Whereas BaZr0.44Ce0.35Y0.2O3-α (BZCY542) showed a higher proton mobility than BaZr0.5Ce0.4Y0.1O3-α (BZCY541) and retained the highest proton conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600 o C as well as excellent chemical stability under 80 % steam for 200 hours. These results suggest Ba and Sr at A-site have different effects on hydration and proton mobility. This paper discusses these aspects based on experimental results as well as steam electrolysis using SZCY-541 and BZCY542 as electrolytes. . |
| 58. | Hiroshige Matsumoto, Proton Ceramic Fuel Cells and Steam Electrolyzers for Hydrogen, Japan Norway Science Week 2015, 2015.05, [URL]. |
| 59. | KWATI LEONARD, Hiroshige Matsumoto, Yuji Okuyama, Young-Sung Lee, Proton Conduction and Concentration in Ba and Sr Cerate-Zirconate Solid Solution with different Y doping level, Solid State Protonic Conductors-17, 2014.09, [URL]. |
| 60. | Yuji Okuyama, Hiroshige Matsumoto, KWATI LEONARD, Young-Sung Lee, Incorporation of Proton in SrZr₀.₉-xY₀.₁O₃-δ, Solid State Protonic Conductors-17, 2014.09, [URL]. |
| 61. | Young-Sung Lee, Hiroshige Matsumoto, Yuji Okuyama, KWATI LEONARD, Influence of transition metal doping on the electrical properties of (Ba,Sr)(Ce,Zr)₀.₉Y₀.₁O₀-δ -based oxides, Solid State Protonic Conductors-17, 2014.09, [URL]. |
| 62. | Hiroshige Matsumoto, Yuji Okuyama, KWATI LEONARD, Young-Sung Lee, Intermadiate Temperature Steam Electrolysis Using Proton-conducting Provuskite for Hydorogen Productin, Solid State Protonic Conductors-17, 2014.09, [URL]. |
| 63. | KWATI LEONARD, Hiroshige Matsumoto, Yuji Okuyama, Young-Sung Lee, Proton Conduction in SZCY and BZCY systems , 第９回固体イオニクスセミナー, 2014.09. |
| 64. | KWATI LEONARD, Hiroshige Matsumoto, Influence of transition metal doping on proton conducting perovskites, 第51回化学関連支部合同九州大会, 2014.06. |
| 65. | Hiroshige Matsumoto, Proton-conducting oxides for solid oxide fuel cells and steam electrolysis, The 7th German-Italian-Japanese Meeting , 2014.06. |
| 66. | Hiroshige Matsumoto, Intermediate temperature steam electrolysis using proton-conducting oxide, 94th Annual Meeting of the Chemical Society of Japan, 28th Mar, Nagoya, Japan. |
| 67. | Hiroshige Matsumoto, Novel nano-surface proton conductor and application to hydrogen production via water electrolysis, COI-Forum(COI STREAM), 13rd Mar, Tokyo, Japan. |
| 68. | Young-Sung Lee, Yuji Okuyama, Hiroshige Matsumoto, The effect of transition metal addition on the ionic properties of proton conducting perovskites, International Conference on Hydrogen Production 2014, 2014.02. |
| 69. | Young-Sung Lee, Yuji Okuyama, Hiroshige Matsumoto, Effect of Transition Metal Doping on the Electrical Properties of Perovskite Oxides, The 30th Japan-Korea International Seminar on Ceramics, 2013.11. |
| 70. | Young-Sung Lee, 畑田直行, 酒井孝明, 松本広重, Effect of transition metal doping on proton conduction properties of alkali earth cerates and zirconates, 第３９回固体イオニクス討論会, 2013.11. |
| 71. | Hiroshige Matsumoto, Science and technology for environment, the lecture on Engineering Academy of Japan, Kyushu branch, 18th Oct, Fukuoka, Japan. |
| 72. | Hiroyuki Oda, Takehiro Yoneda, Yuji Okuyama, Takaaki, Nanostructure electrodes prepared via planetary bead-milling and use for PCFC, Annual Meeting of the Electrochemical Society of Japan(Fall, 2013), 27th Sep, Tokyo, Japan. |
| 73. | LeeYoung-Sung,HatadaNaoyuki,OkuyamaYuji and MatsumotoHiroshige, Effect of transition metal doping on the electrical properties of proton conducting perovskites, Annual Meeting of the Electrochemical Society of Japan(Fall, 2013), 27th Sep, Tokyo, Japan. |
| 74. | Hiroshige Matsumoto, Steam Electrolysis for Hydrogen Production Using Proton Conducting Oxides, Kyocera Technical Meeting, 2013.09. |
| 75. | Hiroshige Matsumoto, Seok-Jun KIM, Takaaki Sakai, Jun-ichi HAMAGAMI, Yuji Okuyama, WATER ELECTROLYSIS USING WATER-ABSORBING POROUS ELECTROLYTE CELL, Innovative Materials for Processes in Energy Systems 2013, 2013.09. |
| 76. | Hiroshige Matsumoto, Impact of transition metal doping on proton conduction properties of alkali earth cerates and zirconates , International Workshop on Protonic Ceramic Fuel Cells Status & Prospects, 2013.07. |
| 77. | Kaori Isa, Yuji Okuyama, Takaaki Sakai and Hiroshige Matsumoto, Development of electrochemical hydrogen production devices using a La-based proton conducting oxide, The 50th joint meeting of chemical branches in Kyushu, 6th July, Kiyakyushu, Japan. |
| 78. | Takehiro Yoneda, Yuji Okuyama and Hiroshige Matsumoto, Proton solubility and electrical properties of BaCe0.8-xZrxY0.2O3-δ, The 50th joint meeting of chemical branches in Kyushu, 6th July, Kitakyushu Japan. |
| 79. | Young-Sung Lee, Naoyuki Hatada, Takaaki Sakai, Yuji Okuyama, Jin-Won Park, Hiroshige Matsumoto, EFFECT OF TRANSITION METAL DOPING ON THE ELECTRICAL PROPERTIES OF SrZr0.9Y0.1O3-δ-BASED OXIDES, The 19th International Conference on Solid State Ionics, 2013.06. |
| 80. | Yuji Okuyama, Shohei Ikeda, Takaaki Sakai, Hiroshige Matsumoto, INCORPORATION OF PROTON INTO LA0.9SR0.1(MxM’1-x)O3-δ(M, M’=Yb, Y, In) , The 19th International Conference on Solid State Ionics, 2013.06. |
| 81. | Takaaki Sakai, Kaori Isa, Maki Matsuoka, Takeshi Kozai, Yuji Okuyama, Tatsumi Ishihara, HIROSHIGE MATSUMOTO, ELECTROCHEMICAL HYDROGEN PUMPING USING Ba DOPED LaYbO3 TYPE PROTON CONDUCTING ELECTROLYTE, The 19th International Conference on Solid State Ionics, 2013.06. |
| 82. | Hiroyuki Oda, Takaaki Sakai, Yuji Okuyama, Hiroshige Matsumoto, PREPARATION OF NANO-STRUCTURED CATHODE FOR PCFC BY BEAD-MILLING METHOD, The 19th International Conference on Solid State Ionics, 2013.06. |
| 83. | Hiroshige Matsumoto, Takaaki Sakai, Shotaro Matsushita, Keita Arakawa, Yuji Okuyama, Tatsumi Ishihara, STEAM ELECTRTOLYSIS USING Sr(Zr,Ce,Y)O3-BASED PROTON-CONDUCTING OXIDES, The 19th International Conference on Solid State Ionics, 2013.06. |
Unauthorized reprint of the contents of this database is prohibited.