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Papers by Pramote Puengjinda

Journal of Physics: Conference Series, 2022

Nowadays, activated carbon were successfully synthesized from biomass, Activated nanoporous carbo... more Nowadays, activated carbon were successfully synthesized from biomass, Activated nanoporous carbon have been widely for several applications such as solution to air pollution, solution to water pollution. In this work, study the effects of pyrolysis temperature of activated carbon synthesized from coconut shell, coconut leaves, coconut bracts, cattail flower, cattail leaves, mangosteen bracts, durian bracts, corn leaves, eucalyptus bracts, sugarcane leaves and toddy palm bracts. The pyrolysis of various biomass was studied at the temperature of 700-900 °C for 2 h under N2 flow of 100 ml/min. The results showed that biomass types and pyrolysis temperature affects the structural and physicochemical properties of activated carbon such as pore structures, surface functional groups and elemental compositions. activated carbon obtained at 800 °C for 2 h had the highest composed of amorphous phase, porosity and surface area.

Current Applied Science and Technology, 2021

Nanoporous carbon was successfully prepared by hydrothermal carbonization with chemical activatio... more Nanoporous carbon was successfully prepared by hydrothermal carbonization with chemical activation using water hyacinth as a raw material. The porous carbon was produced for the adsorption of methylene blue (MB), which is an organic pollutant in wastewater from several industries. The effect of various parameters such as pH, dye concentration and adsorption period time on dye removal were studied. The highest removal efficiency of MB obtained using WH nanoporous carbon was approximately 96.8-99.9% within an adsorption time between 10 and 30 min. The dye removal capacity increased with increasing of period time during the adsorption test. Moreover, the adsorption kinetics of MB during adsorption process was explained by the Langmuir and Freundlich adsorption isotherms.

IOP Conference Series: Materials Science and Engineering, 2020

N-doped porous carbon materials were produced from palm male flower using hydrothermal carbonizat... more N-doped porous carbon materials were produced from palm male flower using hydrothermal carbonization processes at 200 °C for 24 h followed by N-Doping and carbonization at 700°C for 2 h. N-doping was carried out by impregnation using NH4OH at 0.5, 1.0, 1.5 M and 2 M. Products were characterized by means of chemical composition and morphology using SEM, XPS, and XRD to characterize specific properties such as physical morpholog, porosity, elemental composition on surface and crystalline structure of PMF. After applying hydrothermal carbonization processes, the results showed substantially increased porosity and surface area with suitable microstructure for N-doped electrodes applications. The highest porosity was obtained at NPC–1.5 M.

International Journal of Hydrogen Energy, 2021

Abstract Ni–Fe-alloy-foam supported solid oxide electrolysis cell with an arrangement of nickle a... more Abstract Ni–Fe-alloy-foam supported solid oxide electrolysis cell with an arrangement of nickle and Sc0.1Ce0.005Gd0.005Zr0.89O2 (Ni-SCGZ) cathode, SCGZ electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) anode is successfully fabricated by the sequence wet-chemical coating. The multi-layer cathode with a gradient of thermal expansion coefficient (TEC) is deposited on the alloy-foam support. Two-step firing processes are applied including cathode pre-firing (1373 K, 2 h) and electrolyte sintering (1623 K, 4 h) using slow heating rate enhanced with compressive loading. The fabricated cell shows current density of −0.95 Acm−2 at 1.1 V with H2O:H2 = 70:30 and 1073 K, providing hydrogen production rate at 4.95 × 10−6 mol s−1. However, performance degradation was observed with the rate of 0.08 V h−1, which can be ascribed to the delamination of BSCF anode under operating at high current density.

Journal of The Electrochemical Society, 2020

We have examined the durability of a double-layer hydrogen electrode, consisting of a samaria-dop... more We have examined the durability of a double-layer hydrogen electrode, consisting of a samaria-doped ceria (SDC) scaffold with highly dispersed Ni–Co nanoparticles as the catalyst layer and a thin current collecting layer of Ni–yttria-stabilized zirconia (YSZ) cermet for a reversible solid oxide cell (R-SOC). When steam electrolysis was performed continuously (solid oxide electrolysis cell, SOEC) at 800 °C, a rapid, large increase in the ohmic resistance of the hydrogen electrode side was observed. In contrast, the durability of the hydrogen electrode was found to be improved remarkably by reversible cycling operation between SOEC and solid oxide fuel cell (SOFC) modes, i.e., virtually no degradation over 1200 h. This could be ascribed to a stabilization of the microstructure of the hydrogen electrode. It was also found that the durability of the oxygen electrode, which was based on a composite of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and SDC with an SDC interlayer, was also improved by th...

THE SECOND MATERIALS RESEARCH SOCIETY OF THAILAND INTERNATIONAL CONFERENCE, 2020

Recently, lignocellulosic materials have been widely utilized as feedstocks for several applicati... more Recently, lignocellulosic materials have been widely utilized as feedstocks for several applications such as carbon, biofuels and biochemical productions because of their potentials (i.e. waste reduction, carbon sequestration, renewable). In this study, porous carbon was successfully synthesized from water hyacinth (WHs) via hydrothermal carbonization assisted with chemical activation using Na 2 CO 3 and K 2 CO 3. The hydrothermal carbonization process was studied in the range of 160-200°C for 4-12 h and the hydrothermal chars were then further pyrolyzed under a supply of N 2 flow 100 ml/min at 700-900°C for 2 h. The as-pyrolyzed chars were then activated by two different bases including Na 2 CO 3 and K 2 CO 3 at the ratio of 1.0 (w/w, hydrothermal char: chemical) to obtain highly porous carbon. The results indicated that carbon percentage, surface area and porous structure were improved with the higher hydrothermal temperature showing the best results at 180°C for 8 h. Moreover, the development of pore structure of WHs porous carbon was successfully by chemical activation with K 2 CO 3 .

International Journal of Hydrogen Energy, 2020

h i g h l i g h t s Steam electrolysis in solid oxide electrolysis cell is applied for green hydr... more h i g h l i g h t s Steam electrolysis in solid oxide electrolysis cell is applied for green hydrogen production. New electrolyte is investigated to gain high conductivity and chemical stability. Sc 3þ , Ce 4þ , and Gd 3þ doped zirconia (SCGZ) is a promising electrolyte for solid oxide electrolysis cell. SCGZ is compared with yttria stabilized zirconia and gadolinium doped ceria. Although SCGZ exhibits the highest performance, phase transformation occurs during heat treatment.

E3S Web of Conferences, 2020

Alloy foam-supported SOEC is fabricated. Nickel-iron (Ni-Fe) alloy foam (Porosity: 5-130 ppi) is ... more Alloy foam-supported SOEC is fabricated. Nickel-iron (Ni-Fe) alloy foam (Porosity: 5-130 ppi) is used for cell support. Single thin-cell composed of Ni- Sc0.1Ce0.05Gd0.05Zr0.89O2 (SCGZ) cathode, SCGZ electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3- δ (BSCF) anode is fabricated. Electrode powders are mixed with additives forming as slurry for wet chemical coating. 70%weight content of cermet provides smooth surface and sufficient viscosity to prevent slurry sweep through the porous foam. However, severe cracking is clearly seen on the surface of the cell because of mismatching of thermal expansion coefficient (TEC) during sintering. Therefore, the cell with three cathode layers having TEC gradient (13.83, 13.62 and 13.40 ppmK-1) and %weight content of cermet gradient (70%, 60% and 50%weight) is fabricated. Heating rate and steps are controlled at 0.5˚C/min (600 ˚C), 3˚C/min (800 ˚C) and 1˚C/min (1,300˚C, 4 h) to burn off additives before sintering.

ECS Transactions, 2017

A reversible solid oxide cell (R-SOC) is a reciprocal direct energy converter between hydrogen an... more A reversible solid oxide cell (R-SOC) is a reciprocal direct energy converter between hydrogen and electricity (1). We have engaged in the research and development of high-performance electrodes with novel architecture for the R-SOC (2-9). A mixed conducting samaria-doped ceria (CeO2)0.8(SmO1.5)0.2 (denoted as SDC) has been used in both hydrogen and oxygen electrodes. A double-layer (DL) hydrogen electrodes consisting of SDC with highly dispersed Ni0.9Co0.1 catalysts as a catalyst layer and a Ni-SDC cermet attached as a current collecting layer (4, 7) was proposed and tested as a hydrogen electrode. We used an oxygen electrode consisting of a composite of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SDC with SDC interlayer (5), in which SDC acted as a high oxide ionic conductor in oxygen atmosphere. In the present work, we demonstrate that the SDC is a key material in increasing the durability of both electrodes under reversible operations. We examined the durability of the LSCF-SDC electrode with SDC interlayer by using a symmetrical cell: LSCF‒SDC|SDC interlayer|YSZ electrolyte|SDC interlayer|LSCF‒SDC (8, 9). Pure oxygen gas at ambient pressure was supplied to both electrodes. The anodic overpotential (η A) and cathodic overpotential (η C), together with the ohmic resistances of the anode side R A and the cathode side R C, were measured by the current-interruption method with the use of a Pt/air reference electrode. The symmetrical cell was operated at 900 °C and a constant current density of 0.5 A cm−2. It was found that the values of η A and η C were virtually constant over whole operation of 5500 h. In contrast, the value of R C increased somewhat markedly, although the change in the R A was very small. Figure 1 shows the elemental distribution of Ce, Sr, and Zr for a cross-section of the LSCF‒SDC/SDC interlayer/YSZ region observed by SEM equipped with EDX. For the pristine electrode (Fig. 1(A)), we confirmed negligible inter-diffusion of Sr and Zr components at the LSCF‒SDC/SDC interlayer/YSZ. This is ascribed, with certainty, to a low fabrication temperature (1050 °C for 1 h). On the anode side after 5500 h of operation (Fig. 1(B)), the Sr component penetrated into the SDC interlayer with a layer-like distribution, which could be ascribed to rapid diffusion along the sub-layer of the SDC. It is noteworthy that the presence of Sr was limited within the SDC interlayer on the anode side, whereas the Sr component from the cathode reached the YSZ surface just below the SDC interlayer. It was suggested that a rapid diffusion of Sr over the YSZ surface could form SrZrO3, leading to the increase in R C. Because the concentration of Sr was found to be high in the vicinity of defects (dips or voids) of the SDC interlayer, the formation of a dense, uniform SDC interlayer is very important to obtain high durability with high performance in R-SOCs. We are performing the durability test of a full cell with the configuration: DL H2 electrode│YSZ or ScSZ│SDC interlayer│O2 electrode. The initial IR-free applied voltage at 0.5 A cm−2 was 1.16 V at 800 °C and 1.24 V at 750 °C. Effects of microstructure of DL hydrogen electrodes on the durability will be discussed. This work was supported by the funds for “Advanced Low Carbon Technology Research and Development Program” (ALCA) from the Japan Science and Technology Agency (JST). References 1. S. D. Ebbesen, S. H. Jensen, A. Hauch, and M. B. Mogensen, Chem. Rev., 114, 10697 (2014). 2. H. Uchida, N. Osada, and M. Watanabe, Electrochem. Solid-State Lett., 7, A500 (2004). 3. N. Osada, H. Uchida, and M. Watanabe, J. Electrochem. Soc., 153, A816 (2006). 4. H. Uchida, S. Watanabe, Y. Tao, N. Osada, and M. Watanabe, ECS Trans., 7 (1), 365 (2007). 5. Y. Tao, H. Nishino, S. Ashidate, H. Kokubo, M. Watanabe, and H. Uchida, Electrochim. Acta, 54, 3309 (2009). 6. R. Nishida, P. Puengjinda, H. Nishino, K. Kakinuma, M. E. Brito, M. Watanabe, and H. Uchida, RSC Adv., 4, 16260 (2014). 7. H. Uchida, P. Puengjinda, K. Miyano, K. Shimura, H. Nishino, K. Kakinuma, M. E. Brito, and M. Watanabe, ECS Trans., 68 (1), 3307 (2015). 8. K. Shimura, H. Nishino, K. Kakinuma, M. E. Brito, and H. Uchida, Electrochim. Acta, 225, 114 (2017). 9. K. Shimura, H. Nishino, K. Kakinuma, M. E. Brito, and H. Uchida, J. Ceram. Soc. Jpn., in press. Figure 1

ECS Transactions, 2015

We have developed high performance electrodes for reversible SOEC/SOFCs. Double-layer hydrogen el... more We have developed high performance electrodes for reversible SOEC/SOFCs. Double-layer hydrogen electrodes, consisting of a mixed conducting samaria-doped ceria (SDC) with highly dispersed Ni–Co catalysts as the catalyst layer (CL) and, on top of it, a thin Ni–SDC cermet as the current collecting layer (CCL), exhibited highly reversible performance at 800°C by controlling the microstructure. We have also succeeded in enhancing the reversible performances of LSCF–SDC composite oxygen electrodes accompanied by high durability.

ECS Transactions, 2013

For the hydrogen electrode in the solid oxide electrolysis cell (SOEC), nanometer-sized Ni cataly... more For the hydrogen electrode in the solid oxide electrolysis cell (SOEC), nanometer-sized Ni catalysts were highly dispersed on samaria-doped ceria (SDC). It was found that the current density on Ni-dispersed SDC at 900 °C and the potential of ‒1.0 V vs. air increased by 1.5 times with decreasing the Ni particle size from 70 nm to 40 nm, even when the Ni-loading was decreased from 17 vol.% to 8 vol.%.

ECS Transactions, 2011

A composite anode consisting of Y-doped SrTiO3 (YST) as an electron conducting phase with ceramic... more A composite anode consisting of Y-doped SrTiO3 (YST) as an electron conducting phase with ceramic oxides is currently a promising candidate to overcome the shortcoming of Ni-based anode. The composite anodes with various additive oxides such as samaria-doped ceria (SDC), yttria-stabilized zirconia (YSZ), and scandia-stabilized zirconia (ScCeSZ) were prepared to evaluate the electrocatalytic performance in both hydrogen and methane fuels. The composite of YST-SDC showed the excellent performance among all composites investigated due to the superior in catalytic activity of SDC towards the oxidation of fuels. Moreover, the addition of some portions of nickel in anode composite could remarkably enhance the electrochemical performance of the anode. By 10 wt% of nickel oxide loading, the composite showed significantly increased performance in humidified hydrogen and methane without the degradation over 20 h.

Journal of the European Ceramic Society, 2012

Abstract The microstructural change in composite of nickel oxide and scandia-stabilized zirconia ... more Abstract The microstructural change in composite of nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) under a reducing atmosphere was observed by scanning electron microscopy (SEM). The morphological transformation was noticeable after high-temperature treatment with the formation of two peculiar microstructures; i.e ., fibrous zirconia and metallic nickel with wrinkled surface. It was suggested that partial reduction of the nickel species dissolved in ScSZ lattice triggered the formation of these characteristic morphologies. The growth of fibrous zirconia appeared to be promoted via interfacial reaction between the metallic Ni particles and the zirconia phase. The agglomeration of metallic nickel proceeded by the reduction at high temperatures and then the surface was transformed to the wrinkled morphology. The unique wrinkled pattern was often observed for the large agglomerated nickel particles. This drastic change in Ni-ScSZ microstructure upon the high-temperature reduction degraded the electrochemical performance of solid oxide fuel cells.

Journal of Power Sources, 2012

h i g h l i g h t s < The use of Ni/YSTeSDC ceramic anode was proposed to replace Ni-based cermet... more h i g h l i g h t s < The use of Ni/YSTeSDC ceramic anode was proposed to replace Ni-based cermet. < Addition of nickel enhances the electrochemical performance without drawback effects. < The excellence of YSTeSDC ceramic framework could maintain the stable performance. < Ni/YSTeSDC offers certain advantages and highly stable performance in severe conditions.

Journal of Power Sources, 2012

Y-doped SrTiO 3 (YST) is currently used as an effective anode component to solve the shortcomings... more Y-doped SrTiO 3 (YST) is currently used as an effective anode component to solve the shortcomings of conventional Ni-based cermet anodes. In this study, YST-based composite with a different ceramic oxide including samaria-doped ceria (SDC) or yttria-stabilized zirconia (YSZ) was developed as an anode material to evaluate the electrocatalytic performance in hydrogen and methane fuels. The composites showed a good potential in electrical conductivity and compatibility with YSZ electrolyte in the anodic condition. The cell with YST-SDC anode attained the better performance than that with YST-YSZ anode, which was ascribable to the high electrical conductivity and electrocatalytic activity of SDC towards the oxidation of fuels. Addition of nickel remarkably enhanced the electrochemical performance and the stability of the anodes. With 10 wt% of nickel oxide loading, the performance was significantly increased under the operation in humidified hydrogen and methane. Note that in methane fuel, the performance deterioration has not been observed over the short-term operation for 20 h.

Journal of Power Sources, 2011

The effect of crystal structure of yttria-(YSZ) and scandia-stabilized zirconia (ScSZ) in nickel-... more The effect of crystal structure of yttria-(YSZ) and scandia-stabilized zirconia (ScSZ) in nickel-based SOFC anodes was investigated in relation with carbon deposition and oxidation behavior in methane fuel. The lattice parameter of the zirconia decreased by the dissolution of 1-2 mol%Ni to YSZ and ScSZ. For Ni-doped ScSZ, the lattice parameter of the zirconia increased by the Ni dissolution, and the crystal structure of the zirconia was modified after reduction treatment. New finer Ni particles were formed around original Ni grains accompanied by the decrease in Ni solubility to ScSZ after reduction treatment. Carbon deposition was initiated near the boundary between Ni particles and YSZ (or ScSZ) substrate in dry methane atmosphere. Furthermore, the rod-shaped carbon was observed to grow from the new finer Ni particles on the ScSZ substrate. On the other hand, a large amount of amorphous carbon was promoted to be deposited on Ni-YSZ cermet at a high temperature of 1273 K. The amorphous carbon, however, was oxidized at lower temperatures than graphite. The carbon deposition and oxidation behavior was strongly affected by the morphology and crystallinity of deposited carbon.

Journal of The Electrochemical Society, 2010

Nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) composite powders were prepared through t... more Nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) composite powders were prepared through two different processes: mechanical powder mixing (PM) and coprecipitation (CP). The effect of calcination temperatures on the crystalline structure of as-prepared powders and the carbon deposition behavior over the cermets were investigated. Due to the finer precipitates obtained from the CP method, the solid-state reaction between NiO and ScSZ in the as-prepared powder was promoted even at low calcination temperatures, resulting in the stabilization of the cubic phase of ScSZ. The temperature-programmed reduction indicated the strong interaction between NiO and ScSZ in the composite subjected to high temperature treatment regardless of the preparation methods, CP and PM. Phase identification was also conducted for the composites after reduction treatment at high temperatures of 1000 and 1400°C. After reducing at 1400°C, a part of ScSZ in the composite from the CP method transformed from the cubic to the rhombohedral phase, whereas the cubic phase was stable for the composite from the PM method. In addition, the carbon deposition over the sample from the CP method was promoted due to the large surface area of Ni. However, the electrochemical performance of single cells was independent of the cermet anodes from different methods with a supply of both H 2 and CH 4 fuels.

Kyoto University (京都大学)0048新制・課程博士博士(工学)甲第16869号工博第3590号新制||工||1542(附属図書館)29544京都大学大学院工学研究科物質エネルギ... more Kyoto University (京都大学)0048新制・課程博士博士(工学)甲第16869号工博第3590号新制||工||1542(附属図書館)29544京都大学大学院工学研究科物質エネルギー化学専攻(主査)教授 江口 浩一, 教授 安部 武志, 教授 陰山 洋学位規則第4条第1項該

Journal of The Electrochemical Society, 2017

We have developed high-performance double-layer (DL) hydrogen electrodes for reversible solid oxi... more We have developed high-performance double-layer (DL) hydrogen electrodes for reversible solid oxide cells. The DL hydrogen electrode consisted of mixed conductor, samaria-doped ceria (SDC), with highly dispersed Ni or Ni-Co nanocatalysts as the catalyst layer (CL) and, on top of it, a thin Ni−SDC cermet as the current collecting layer (CCL). The performance of the DL hydrogen electrode was appreciably improved by controlling the microstructure. The use of a thin, porous CCL increased the electronic conducting path to and from the CL, while maintaining sufficient gas-diffusion rates of H 2 and H 2 O, and enlarging the effective reaction zone at the CL. The optimum CCL thickness was found to be 5 μm. The IR-free overpotentials η at the optimized DL hydrogen electrode in humidified hydrogen (p[H 2 O] = 0.4 atm) and T cell = 800 • C were 0.20 and −0.20 V at j = 0.5 and −0.5 A cm −2 , respectively, indicating a highly reversible operation. The use of a full cell with the configuration of Ni 0.9 Co 0.1 /SDC DL hydrogen electrode|YSZ electrolyte|SDC interlayer|LSCF−SDC O 2 electrode led to very promising results for the SOEC operation in which an IR-free electrolytic cell potential of 1.21 V at j = −0.5 A cm −2 and 800 • C was achieved.

Journal of Physics: Conference Series, 2022

Nowadays, activated carbon were successfully synthesized from biomass, Activated nanoporous carbo... more Nowadays, activated carbon were successfully synthesized from biomass, Activated nanoporous carbon have been widely for several applications such as solution to air pollution, solution to water pollution. In this work, study the effects of pyrolysis temperature of activated carbon synthesized from coconut shell, coconut leaves, coconut bracts, cattail flower, cattail leaves, mangosteen bracts, durian bracts, corn leaves, eucalyptus bracts, sugarcane leaves and toddy palm bracts. The pyrolysis of various biomass was studied at the temperature of 700-900 °C for 2 h under N2 flow of 100 ml/min. The results showed that biomass types and pyrolysis temperature affects the structural and physicochemical properties of activated carbon such as pore structures, surface functional groups and elemental compositions. activated carbon obtained at 800 °C for 2 h had the highest composed of amorphous phase, porosity and surface area.

Current Applied Science and Technology, 2021

Nanoporous carbon was successfully prepared by hydrothermal carbonization with chemical activatio... more Nanoporous carbon was successfully prepared by hydrothermal carbonization with chemical activation using water hyacinth as a raw material. The porous carbon was produced for the adsorption of methylene blue (MB), which is an organic pollutant in wastewater from several industries. The effect of various parameters such as pH, dye concentration and adsorption period time on dye removal were studied. The highest removal efficiency of MB obtained using WH nanoporous carbon was approximately 96.8-99.9% within an adsorption time between 10 and 30 min. The dye removal capacity increased with increasing of period time during the adsorption test. Moreover, the adsorption kinetics of MB during adsorption process was explained by the Langmuir and Freundlich adsorption isotherms.

IOP Conference Series: Materials Science and Engineering, 2020

N-doped porous carbon materials were produced from palm male flower using hydrothermal carbonizat... more N-doped porous carbon materials were produced from palm male flower using hydrothermal carbonization processes at 200 °C for 24 h followed by N-Doping and carbonization at 700°C for 2 h. N-doping was carried out by impregnation using NH4OH at 0.5, 1.0, 1.5 M and 2 M. Products were characterized by means of chemical composition and morphology using SEM, XPS, and XRD to characterize specific properties such as physical morpholog, porosity, elemental composition on surface and crystalline structure of PMF. After applying hydrothermal carbonization processes, the results showed substantially increased porosity and surface area with suitable microstructure for N-doped electrodes applications. The highest porosity was obtained at NPC–1.5 M.

International Journal of Hydrogen Energy, 2021

Abstract Ni–Fe-alloy-foam supported solid oxide electrolysis cell with an arrangement of nickle a... more Abstract Ni–Fe-alloy-foam supported solid oxide electrolysis cell with an arrangement of nickle and Sc0.1Ce0.005Gd0.005Zr0.89O2 (Ni-SCGZ) cathode, SCGZ electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) anode is successfully fabricated by the sequence wet-chemical coating. The multi-layer cathode with a gradient of thermal expansion coefficient (TEC) is deposited on the alloy-foam support. Two-step firing processes are applied including cathode pre-firing (1373 K, 2 h) and electrolyte sintering (1623 K, 4 h) using slow heating rate enhanced with compressive loading. The fabricated cell shows current density of −0.95 Acm−2 at 1.1 V with H2O:H2 = 70:30 and 1073 K, providing hydrogen production rate at 4.95 × 10−6 mol s−1. However, performance degradation was observed with the rate of 0.08 V h−1, which can be ascribed to the delamination of BSCF anode under operating at high current density.

Journal of The Electrochemical Society, 2020

We have examined the durability of a double-layer hydrogen electrode, consisting of a samaria-dop... more We have examined the durability of a double-layer hydrogen electrode, consisting of a samaria-doped ceria (SDC) scaffold with highly dispersed Ni–Co nanoparticles as the catalyst layer and a thin current collecting layer of Ni–yttria-stabilized zirconia (YSZ) cermet for a reversible solid oxide cell (R-SOC). When steam electrolysis was performed continuously (solid oxide electrolysis cell, SOEC) at 800 °C, a rapid, large increase in the ohmic resistance of the hydrogen electrode side was observed. In contrast, the durability of the hydrogen electrode was found to be improved remarkably by reversible cycling operation between SOEC and solid oxide fuel cell (SOFC) modes, i.e., virtually no degradation over 1200 h. This could be ascribed to a stabilization of the microstructure of the hydrogen electrode. It was also found that the durability of the oxygen electrode, which was based on a composite of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and SDC with an SDC interlayer, was also improved by th...

THE SECOND MATERIALS RESEARCH SOCIETY OF THAILAND INTERNATIONAL CONFERENCE, 2020

Recently, lignocellulosic materials have been widely utilized as feedstocks for several applicati... more Recently, lignocellulosic materials have been widely utilized as feedstocks for several applications such as carbon, biofuels and biochemical productions because of their potentials (i.e. waste reduction, carbon sequestration, renewable). In this study, porous carbon was successfully synthesized from water hyacinth (WHs) via hydrothermal carbonization assisted with chemical activation using Na 2 CO 3 and K 2 CO 3. The hydrothermal carbonization process was studied in the range of 160-200°C for 4-12 h and the hydrothermal chars were then further pyrolyzed under a supply of N 2 flow 100 ml/min at 700-900°C for 2 h. The as-pyrolyzed chars were then activated by two different bases including Na 2 CO 3 and K 2 CO 3 at the ratio of 1.0 (w/w, hydrothermal char: chemical) to obtain highly porous carbon. The results indicated that carbon percentage, surface area and porous structure were improved with the higher hydrothermal temperature showing the best results at 180°C for 8 h. Moreover, the development of pore structure of WHs porous carbon was successfully by chemical activation with K 2 CO 3 .

International Journal of Hydrogen Energy, 2020

h i g h l i g h t s Steam electrolysis in solid oxide electrolysis cell is applied for green hydr... more h i g h l i g h t s Steam electrolysis in solid oxide electrolysis cell is applied for green hydrogen production. New electrolyte is investigated to gain high conductivity and chemical stability. Sc 3þ , Ce 4þ , and Gd 3þ doped zirconia (SCGZ) is a promising electrolyte for solid oxide electrolysis cell. SCGZ is compared with yttria stabilized zirconia and gadolinium doped ceria. Although SCGZ exhibits the highest performance, phase transformation occurs during heat treatment.

E3S Web of Conferences, 2020

Alloy foam-supported SOEC is fabricated. Nickel-iron (Ni-Fe) alloy foam (Porosity: 5-130 ppi) is ... more Alloy foam-supported SOEC is fabricated. Nickel-iron (Ni-Fe) alloy foam (Porosity: 5-130 ppi) is used for cell support. Single thin-cell composed of Ni- Sc0.1Ce0.05Gd0.05Zr0.89O2 (SCGZ) cathode, SCGZ electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3- δ (BSCF) anode is fabricated. Electrode powders are mixed with additives forming as slurry for wet chemical coating. 70%weight content of cermet provides smooth surface and sufficient viscosity to prevent slurry sweep through the porous foam. However, severe cracking is clearly seen on the surface of the cell because of mismatching of thermal expansion coefficient (TEC) during sintering. Therefore, the cell with three cathode layers having TEC gradient (13.83, 13.62 and 13.40 ppmK-1) and %weight content of cermet gradient (70%, 60% and 50%weight) is fabricated. Heating rate and steps are controlled at 0.5˚C/min (600 ˚C), 3˚C/min (800 ˚C) and 1˚C/min (1,300˚C, 4 h) to burn off additives before sintering.

ECS Transactions, 2017

A reversible solid oxide cell (R-SOC) is a reciprocal direct energy converter between hydrogen an... more A reversible solid oxide cell (R-SOC) is a reciprocal direct energy converter between hydrogen and electricity (1). We have engaged in the research and development of high-performance electrodes with novel architecture for the R-SOC (2-9). A mixed conducting samaria-doped ceria (CeO2)0.8(SmO1.5)0.2 (denoted as SDC) has been used in both hydrogen and oxygen electrodes. A double-layer (DL) hydrogen electrodes consisting of SDC with highly dispersed Ni0.9Co0.1 catalysts as a catalyst layer and a Ni-SDC cermet attached as a current collecting layer (4, 7) was proposed and tested as a hydrogen electrode. We used an oxygen electrode consisting of a composite of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SDC with SDC interlayer (5), in which SDC acted as a high oxide ionic conductor in oxygen atmosphere. In the present work, we demonstrate that the SDC is a key material in increasing the durability of both electrodes under reversible operations. We examined the durability of the LSCF-SDC electrode with SDC interlayer by using a symmetrical cell: LSCF‒SDC|SDC interlayer|YSZ electrolyte|SDC interlayer|LSCF‒SDC (8, 9). Pure oxygen gas at ambient pressure was supplied to both electrodes. The anodic overpotential (η A) and cathodic overpotential (η C), together with the ohmic resistances of the anode side R A and the cathode side R C, were measured by the current-interruption method with the use of a Pt/air reference electrode. The symmetrical cell was operated at 900 °C and a constant current density of 0.5 A cm−2. It was found that the values of η A and η C were virtually constant over whole operation of 5500 h. In contrast, the value of R C increased somewhat markedly, although the change in the R A was very small. Figure 1 shows the elemental distribution of Ce, Sr, and Zr for a cross-section of the LSCF‒SDC/SDC interlayer/YSZ region observed by SEM equipped with EDX. For the pristine electrode (Fig. 1(A)), we confirmed negligible inter-diffusion of Sr and Zr components at the LSCF‒SDC/SDC interlayer/YSZ. This is ascribed, with certainty, to a low fabrication temperature (1050 °C for 1 h). On the anode side after 5500 h of operation (Fig. 1(B)), the Sr component penetrated into the SDC interlayer with a layer-like distribution, which could be ascribed to rapid diffusion along the sub-layer of the SDC. It is noteworthy that the presence of Sr was limited within the SDC interlayer on the anode side, whereas the Sr component from the cathode reached the YSZ surface just below the SDC interlayer. It was suggested that a rapid diffusion of Sr over the YSZ surface could form SrZrO3, leading to the increase in R C. Because the concentration of Sr was found to be high in the vicinity of defects (dips or voids) of the SDC interlayer, the formation of a dense, uniform SDC interlayer is very important to obtain high durability with high performance in R-SOCs. We are performing the durability test of a full cell with the configuration: DL H2 electrode│YSZ or ScSZ│SDC interlayer│O2 electrode. The initial IR-free applied voltage at 0.5 A cm−2 was 1.16 V at 800 °C and 1.24 V at 750 °C. Effects of microstructure of DL hydrogen electrodes on the durability will be discussed. This work was supported by the funds for “Advanced Low Carbon Technology Research and Development Program” (ALCA) from the Japan Science and Technology Agency (JST). References 1. S. D. Ebbesen, S. H. Jensen, A. Hauch, and M. B. Mogensen, Chem. Rev., 114, 10697 (2014). 2. H. Uchida, N. Osada, and M. Watanabe, Electrochem. Solid-State Lett., 7, A500 (2004). 3. N. Osada, H. Uchida, and M. Watanabe, J. Electrochem. Soc., 153, A816 (2006). 4. H. Uchida, S. Watanabe, Y. Tao, N. Osada, and M. Watanabe, ECS Trans., 7 (1), 365 (2007). 5. Y. Tao, H. Nishino, S. Ashidate, H. Kokubo, M. Watanabe, and H. Uchida, Electrochim. Acta, 54, 3309 (2009). 6. R. Nishida, P. Puengjinda, H. Nishino, K. Kakinuma, M. E. Brito, M. Watanabe, and H. Uchida, RSC Adv., 4, 16260 (2014). 7. H. Uchida, P. Puengjinda, K. Miyano, K. Shimura, H. Nishino, K. Kakinuma, M. E. Brito, and M. Watanabe, ECS Trans., 68 (1), 3307 (2015). 8. K. Shimura, H. Nishino, K. Kakinuma, M. E. Brito, and H. Uchida, Electrochim. Acta, 225, 114 (2017). 9. K. Shimura, H. Nishino, K. Kakinuma, M. E. Brito, and H. Uchida, J. Ceram. Soc. Jpn., in press. Figure 1

ECS Transactions, 2015

We have developed high performance electrodes for reversible SOEC/SOFCs. Double-layer hydrogen el... more We have developed high performance electrodes for reversible SOEC/SOFCs. Double-layer hydrogen electrodes, consisting of a mixed conducting samaria-doped ceria (SDC) with highly dispersed Ni–Co catalysts as the catalyst layer (CL) and, on top of it, a thin Ni–SDC cermet as the current collecting layer (CCL), exhibited highly reversible performance at 800°C by controlling the microstructure. We have also succeeded in enhancing the reversible performances of LSCF–SDC composite oxygen electrodes accompanied by high durability.

ECS Transactions, 2013

For the hydrogen electrode in the solid oxide electrolysis cell (SOEC), nanometer-sized Ni cataly... more For the hydrogen electrode in the solid oxide electrolysis cell (SOEC), nanometer-sized Ni catalysts were highly dispersed on samaria-doped ceria (SDC). It was found that the current density on Ni-dispersed SDC at 900 °C and the potential of ‒1.0 V vs. air increased by 1.5 times with decreasing the Ni particle size from 70 nm to 40 nm, even when the Ni-loading was decreased from 17 vol.% to 8 vol.%.

ECS Transactions, 2011

A composite anode consisting of Y-doped SrTiO3 (YST) as an electron conducting phase with ceramic... more A composite anode consisting of Y-doped SrTiO3 (YST) as an electron conducting phase with ceramic oxides is currently a promising candidate to overcome the shortcoming of Ni-based anode. The composite anodes with various additive oxides such as samaria-doped ceria (SDC), yttria-stabilized zirconia (YSZ), and scandia-stabilized zirconia (ScCeSZ) were prepared to evaluate the electrocatalytic performance in both hydrogen and methane fuels. The composite of YST-SDC showed the excellent performance among all composites investigated due to the superior in catalytic activity of SDC towards the oxidation of fuels. Moreover, the addition of some portions of nickel in anode composite could remarkably enhance the electrochemical performance of the anode. By 10 wt% of nickel oxide loading, the composite showed significantly increased performance in humidified hydrogen and methane without the degradation over 20 h.

Journal of the European Ceramic Society, 2012

Abstract The microstructural change in composite of nickel oxide and scandia-stabilized zirconia ... more Abstract The microstructural change in composite of nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) under a reducing atmosphere was observed by scanning electron microscopy (SEM). The morphological transformation was noticeable after high-temperature treatment with the formation of two peculiar microstructures; i.e ., fibrous zirconia and metallic nickel with wrinkled surface. It was suggested that partial reduction of the nickel species dissolved in ScSZ lattice triggered the formation of these characteristic morphologies. The growth of fibrous zirconia appeared to be promoted via interfacial reaction between the metallic Ni particles and the zirconia phase. The agglomeration of metallic nickel proceeded by the reduction at high temperatures and then the surface was transformed to the wrinkled morphology. The unique wrinkled pattern was often observed for the large agglomerated nickel particles. This drastic change in Ni-ScSZ microstructure upon the high-temperature reduction degraded the electrochemical performance of solid oxide fuel cells.

Journal of Power Sources, 2012

h i g h l i g h t s < The use of Ni/YSTeSDC ceramic anode was proposed to replace Ni-based cermet... more h i g h l i g h t s < The use of Ni/YSTeSDC ceramic anode was proposed to replace Ni-based cermet. < Addition of nickel enhances the electrochemical performance without drawback effects. < The excellence of YSTeSDC ceramic framework could maintain the stable performance. < Ni/YSTeSDC offers certain advantages and highly stable performance in severe conditions.

Journal of Power Sources, 2012

Y-doped SrTiO 3 (YST) is currently used as an effective anode component to solve the shortcomings... more Y-doped SrTiO 3 (YST) is currently used as an effective anode component to solve the shortcomings of conventional Ni-based cermet anodes. In this study, YST-based composite with a different ceramic oxide including samaria-doped ceria (SDC) or yttria-stabilized zirconia (YSZ) was developed as an anode material to evaluate the electrocatalytic performance in hydrogen and methane fuels. The composites showed a good potential in electrical conductivity and compatibility with YSZ electrolyte in the anodic condition. The cell with YST-SDC anode attained the better performance than that with YST-YSZ anode, which was ascribable to the high electrical conductivity and electrocatalytic activity of SDC towards the oxidation of fuels. Addition of nickel remarkably enhanced the electrochemical performance and the stability of the anodes. With 10 wt% of nickel oxide loading, the performance was significantly increased under the operation in humidified hydrogen and methane. Note that in methane fuel, the performance deterioration has not been observed over the short-term operation for 20 h.

Journal of Power Sources, 2011

The effect of crystal structure of yttria-(YSZ) and scandia-stabilized zirconia (ScSZ) in nickel-... more The effect of crystal structure of yttria-(YSZ) and scandia-stabilized zirconia (ScSZ) in nickel-based SOFC anodes was investigated in relation with carbon deposition and oxidation behavior in methane fuel. The lattice parameter of the zirconia decreased by the dissolution of 1-2 mol%Ni to YSZ and ScSZ. For Ni-doped ScSZ, the lattice parameter of the zirconia increased by the Ni dissolution, and the crystal structure of the zirconia was modified after reduction treatment. New finer Ni particles were formed around original Ni grains accompanied by the decrease in Ni solubility to ScSZ after reduction treatment. Carbon deposition was initiated near the boundary between Ni particles and YSZ (or ScSZ) substrate in dry methane atmosphere. Furthermore, the rod-shaped carbon was observed to grow from the new finer Ni particles on the ScSZ substrate. On the other hand, a large amount of amorphous carbon was promoted to be deposited on Ni-YSZ cermet at a high temperature of 1273 K. The amorphous carbon, however, was oxidized at lower temperatures than graphite. The carbon deposition and oxidation behavior was strongly affected by the morphology and crystallinity of deposited carbon.

Journal of The Electrochemical Society, 2010

Nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) composite powders were prepared through t... more Nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) composite powders were prepared through two different processes: mechanical powder mixing (PM) and coprecipitation (CP). The effect of calcination temperatures on the crystalline structure of as-prepared powders and the carbon deposition behavior over the cermets were investigated. Due to the finer precipitates obtained from the CP method, the solid-state reaction between NiO and ScSZ in the as-prepared powder was promoted even at low calcination temperatures, resulting in the stabilization of the cubic phase of ScSZ. The temperature-programmed reduction indicated the strong interaction between NiO and ScSZ in the composite subjected to high temperature treatment regardless of the preparation methods, CP and PM. Phase identification was also conducted for the composites after reduction treatment at high temperatures of 1000 and 1400°C. After reducing at 1400°C, a part of ScSZ in the composite from the CP method transformed from the cubic to the rhombohedral phase, whereas the cubic phase was stable for the composite from the PM method. In addition, the carbon deposition over the sample from the CP method was promoted due to the large surface area of Ni. However, the electrochemical performance of single cells was independent of the cermet anodes from different methods with a supply of both H 2 and CH 4 fuels.

Kyoto University (京都大学)0048新制・課程博士博士(工学)甲第16869号工博第3590号新制||工||1542(附属図書館)29544京都大学大学院工学研究科物質エネルギ... more Kyoto University (京都大学)0048新制・課程博士博士(工学)甲第16869号工博第3590号新制||工||1542(附属図書館)29544京都大学大学院工学研究科物質エネルギー化学専攻(主査)教授 江口 浩一, 教授 安部 武志, 教授 陰山 洋学位規則第4条第1項該

Journal of The Electrochemical Society, 2017

We have developed high-performance double-layer (DL) hydrogen electrodes for reversible solid oxi... more We have developed high-performance double-layer (DL) hydrogen electrodes for reversible solid oxide cells. The DL hydrogen electrode consisted of mixed conductor, samaria-doped ceria (SDC), with highly dispersed Ni or Ni-Co nanocatalysts as the catalyst layer (CL) and, on top of it, a thin Ni−SDC cermet as the current collecting layer (CCL). The performance of the DL hydrogen electrode was appreciably improved by controlling the microstructure. The use of a thin, porous CCL increased the electronic conducting path to and from the CL, while maintaining sufficient gas-diffusion rates of H 2 and H 2 O, and enlarging the effective reaction zone at the CL. The optimum CCL thickness was found to be 5 μm. The IR-free overpotentials η at the optimized DL hydrogen electrode in humidified hydrogen (p[H 2 O] = 0.4 atm) and T cell = 800 • C were 0.20 and −0.20 V at j = 0.5 and −0.5 A cm −2 , respectively, indicating a highly reversible operation. The use of a full cell with the configuration of Ni 0.9 Co 0.1 /SDC DL hydrogen electrode|YSZ electrolyte|SDC interlayer|LSCF−SDC O 2 electrode led to very promising results for the SOEC operation in which an IR-free electrolytic cell potential of 1.21 V at j = −0.5 A cm −2 and 800 • C was achieved.