The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Wei Liu - One of the best experts on this subject based on the ideXlab platform.
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an easily sintered and chemically stable la2 xmgxce2o7 δ Proton Conductor for high performance solid oxide fuel cells
International Journal of Hydrogen Energy, 2019Co-Authors: Zheng Gong, Jie Hou, Lina Miao, Haidi Tang, Wei LiuAbstract:Abstract Mg-doped La2Ce2O7-δ (LCO) is investigated to develop an easily sintered and chemically stable Proton Conductor for fabricating high-performance solid oxide fuel cells (SOFCs). All La2-xMgxCe2O7-δ ceramics possess a pure fluorite-type structure. The sintering activity of Mg-doped LCO increases obviously, and fully dense La1.85Mg0.15Ce2O7-δ (LMCO) electrolyte membrane is successfully prepared by co-firing at the temperature as low as 1300 °C for 5 h. Besides, LMCO exhibits the highest electrical conductivity of 7.41 × 10−3 S cm−1 in dry air and 1.55 × 10−2 S cm−1 in wet H2 (∼3% H2O) at 700 °C among the investigated oxides, and retains excellent chemical stability against CO2 and H2O. The LMCO-based fuel cell also displays very encouraging power performance, reaching as high as 897 mWcm−2 at 700 °C. The results demonstrate LMCO is a promising alternative as Proton Conductor for achieving both chemically stable and high-performance SOFCs with reduced sintering temperature.
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an easily sintered chemically stable barium zirconate based Proton Conductor for high performance Proton conducting solid oxide fuel cells
Advanced Functional Materials, 2014Co-Authors: Wei Liu, Zhen Shi, Wenping Sun, Mingfei LiuAbstract:Yttrium and indium co-doped barium zirconate is investigated to develop a chemically stable and sintering active Proton Conductor for solid oxide fuel cells (SOFCs). BaZr0.8Y0.2-xInxO3- δ possesses a pure cubic perovskite structure. The sintering activity of BaZr0.8Y0.2-xInxO3- δ increases significantly with In concentration. BaZr0.8Y0.15In0.05O3- δ (BZYI5) exhibits the highest total electrical conductivity among the sintered oxides. BZYI5 also retains high chemical stability against CO2, vapor, and reduction of H2. The good sintering activity, high conductivity, and chemical stability of BZYI5 facilitate the fabrication of durable SOFCs based on a highly conductive BZYI5 electrolyte film by cost-effective ceramic processes. Fully dense BZYI5 electrolyte film is successfully prepared on the anode substrate by a facile drop-coating technique followed by co-firing at 1400 °C for 5 h in air. The BZYI5 film exhibits one of the highest conductivity among the BaZrO3-based electrolyte films with various sintering aids. BZYI5-based single cells output very encouraging and by far the highest peak power density for BaZrO3-based Proton-conducting SOFCs, reaching as high as 379 mW cm−2 at 700 °C. The results demonstrate that Y and In co-doping is an effective strategy for exploring sintering active and chemically stable BaZrO3-based Proton Conductors for high performance Proton-conducting SOFCs.
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samarium and yttrium codoped baceo3 Proton Conductor with improved sinterability and higher electrical conductivity
ACS Applied Materials & Interfaces, 2014Co-Authors: Zhen Shi, Wenping Sun, Zhongtao Wang, Jing Qian, Wei LiuAbstract:Acceptor-doped barium cerate is considered as one of the state-of-the-art high temperature Proton Conductors (HTPCs), and the Proton conductivity of such HTPCs is heavily dependent on the dopant. In this work, a codoping strategy is employed to improve the electrical conductivity and sinterability of BaCeO3-based HTPC. BaCe0.8Sm(x)Y(0.2-x)O(3-δ) (0 ≤ x ≤ 0.2) powders are synthesized by a typical citrate-nitrate combustion method. The XRD and Raman spectra reveal all the compounds have an orthorhombic perovskite structure. The effects of Sm and/or Y doping on the sinterability and electrical conductivity under different atmospheres are carefully investigated. The SEM results of the sintered BaCe0.8Sm(x)Y(0.2-x)O(3-δ) pellets indicate a significant sintering enhancement with increasing Sm concentration. BaCe0.8Sm0.1Y0.1O(3-δ) exhibits the highest electrical conductivity in hydrogen among the BaCe0.8Sm(x)Y(0.2-x)O(3-δ) pellets. Anode-supported BaCe0.8Sm0.1Y0.1O(3-δ) electrolyte membranes are also fabricated via a drop-coating process, and the corresponding single cell exhibits desirable power performance and durability at low temperatures. The results demonstrate that BaCe0.8Sm0.1Y0.1O(3-δ) is a promising Proton Conductor with high conductivity and sufficient sinterability for Proton-conducting solid oxide fuel cells operating at reduced temperatures.
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structural stability of la2ce2o7 as a Proton Conductor a first principles study
Journal of Physical Chemistry C, 2013Co-Authors: Qingping Zhang, Xiao Zheng, Jun Jiang, Wei LiuAbstract:As a promising candidate of a Proton Conductor under reducing atmosphere, La2Ce2O7 has attracted considerable research interest. However, the thermodynamically stable structure of bulk La2Ce2O7 has remained rather unclear. In this paper, first-principles calculations are carried out to resolve this issue. It is found that the lattice of La2Ce2O7 is substantially stabilized by the formation of anion Frenkel defects, i.e., oxygen atoms displaced from their original sites to interstitial regions. Consequently, the bulk La2Ce2O7 favors disordered fluorite configurations over pyrochlore structure. Our calculation results are consistent with the previously reported neutron diffraction patterns. In addition, partial disordering of cations is also likely under experimental conditions. We then explore the possible Proton transfer pathways inside bulk La2Ce2O7. It is revealed that the partial disordering in La2Ce2O7 increases the energy barriers of Proton transfer pathways.
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chemically stable and easily sintered high temperature Proton Conductor bazr0 8in0 2o3 δ for solid oxide fuel cells
Journal of Power Sources, 2013Co-Authors: Wei Liu, Zhen Shi, Wenping Sun, Zhiwen ZhuAbstract:Abstract Barium zirconate-based high-temperature Proton Conductors (HTPCs) exhibit excellent chemical stability in atmospheres containing CO 2 or water vapor. However, such HPTCs haven't been widely used as electrolyte materials for solid oxide fuel cells (SOFCs) due to their poor sintering activity. In this work, indium is selected as a dopant to improve the sintering activity of barium zirconate. BaZr 0.8 In 0.2 O 3− δ (BZI) powders with a pure cubic perovskite structure are synthesized via a typical citric acid–nitrate gel combustion process. The SEM results show that BZI exhibits improved sintering activity compared to the state-of-the-art Proton Conductor BaZr 0.8 Y 0.2 O 3− δ (BZY), and fully dense BZI pellets with increased grain size are obtained after sintered at 1600 °C in air. Moreover, BZI also keeps sufficiently high chemical stability as BZY. The electrical conductivity of BZI under various atmospheres is investigated by electrochemical impedance spectroscopy (EIS) in detail. The total conductivity achieves 1.0 × 10 −3 S cm −1 at 700 °C in wet H 2 (3% H 2 O). Dense BZI electrolyte films are successfully fabricated on the anode substrates by a dry-pressing method after sintered at 1400 °C for 5 h in air. Single cells with dense BZI electrolyte films are also assembled and tested to further evaluate the feasibility of BZI as an electrolyte material for Proton-conducting SOFCs.
Hiroyasu Iwahara - One of the best experts on this subject based on the ideXlab platform.
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electrochemical hydrogen pump using a high temperature type Proton Conductor improvement of pumping capacity
Solid State Ionics, 2001Co-Authors: Hiroshige Matsumoto, S Hamajima, Hiroyasu IwaharaAbstract:Abstract In the electrochemical hydrogen pump based on SrCe 0.95 Yb 0.05 O 3− α Proton Conductor cell, effects of water vapor supplied to the cathode and operation temperature on the pumping characteristics were examined. Hydrogen-pumping capacity could be enhanced by increasing water vapor supply to the cathode and by reducing operation temperature within the examined range of 700–900°C. Presence of sufficient water vapor at the cathode would keep the current efficiency of the hydrogen pump.
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electrochemical hydrogen pump using srceo3 based Proton Conductor effect of water vapor at the cathode on the pumping capacity
Journal of The Electrochemical Society, 2001Co-Authors: Hiroshige Matsumoto, S Hamajima, T Yajima, Hiroyasu IwaharaAbstract:Electrochemical pumping of hydrogen through high temperature-type Proton-conducting solid electrolytes has been studied. The effect of water vapor introduced to the cathode on the hydrogen-pumping capacity of the SrCe 0.95 Yb 0.05 O 3-α Proton Conductor cell was investigated in the present study. The pumping capacity of the cell was greatly enhanced when water vapor was introduced to the cathode. The water vapor was consumed at the cathode due to the minor partial oxide ionic conduction in the electrolyte. The role of the water vapor at the cathode in the hydrogen pump is discussed.
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A hydrocarbon sensor using a high temperature-type Proton Conductor
Journal of Applied Electrochemistry, 1994Co-Authors: Takashi Hibino, Hiroyasu IwaharaAbstract:Using a CaZrO3-based Proton Conductor as a solid electrolyte, a hydrocarbon sensor has been constructed. The test cell with gold metal and La0.6Ba0.4CoO3 oxide as electrode material gives rise to stable e.m.f.'s on introducing air containing hydrocarbons (CH4, C2H6 or C3H8). This sensing mechanism is based on a steam concentration cell, which results from the difference in combustion activity for hydrocarbons between two electrode materials.
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Recycling of carbon dioxide using a Proton Conductor as a solid electrolyte
Journal of Applied Electrochemistry, 1994Co-Authors: Takashi Hibino, S. Hamakawa, T. Suzuki, Hiroyasu IwaharaAbstract:Using a Proton Conductor based on SrZrO3 or CaZrO3 as a solid electrolyte, three attempts have been made to react CH4 with CO2 efficiently. When the mixture of CH4 and CO2 was used as a fuel gas for a SOFC, the cell provided stable electric power. Furthermore, the electrochemical hydrogen pump accelerated both the reforming of CH4 with CO2 and the oxidative coupling of CH4 with CO2.
Tilman Schober - One of the best experts on this subject based on the ideXlab platform.
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Transformation of an oxygen ion Conductor to a Proton Conductor by solid state reaction
Solid State Ionics, 2005Co-Authors: Tilman SchoberAbstract:Abstract It is shown that starting from a thin, gas tight layer of an oxygen ion Conductor such as 8YSZ a thin, gas tight layer of a Proton Conductor can be obtained by coating the original layer with BaCO 3 or BaO followed by sintering. Generally, a homogeneous Zr 1– x Y x O 2– y ceramic compound will react with BaO to form the desired Proton Conductor BaZr 1– x Y x O 3– x /2 . This procedure obviates the deposition of Proton conducting layers starting from fine powders which in view of the poor sinterabilty of the common Proton Conductors was a difficult endeavor in the past. It also permits the construction of larger components (reactors etc.) covered with a Proton Conductor. The present technique is also applicable to the formation of CZI10 (CaZr 0.9 In 0.1 O 3–y ) layers. The latter compound is an excellent Proton Conductor for potentiometric purposes and has seen commercial use in hydrogen sensors in molten aluminium (5).
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Electrical Conductivity of the High-Temperature Proton Conductor BaZr0.9Y0.1O2.95
Journal of the American Ceramic Society, 2004Co-Authors: Hans G Bohn, Tilman SchoberAbstract:The impedance of the cubic perovskite BaZr0.9Y0.1O3-δ has been systematically investigated in dry and wet atmospheres at high and low oxygen partial pressures. In the grain interior, conductivity contributions from oxygen ions, electron holes, and Protons can be identified. Below 300°C, Proton conduction dominates and increases linearly with the frozen-in Proton concentration. The Proton mobility, with an activation energy of 0.44 ± 0.01 eV is among the highest ever reported for a perovskite-type oxide Proton Conductor. For dry oxygen atmos-pheres, electron hole conduction dominates with an activation energy of ∼0.9 eV. At temperatures
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High‐Temperature Proton Conductors for the Injection of Hydrogen into a Vacuum
Journal of the American Ceramic Society, 2004Co-Authors: Tilman Schober, Paul MeuffelsAbstract:Tubes of ceramic high-temperature Proton Conductors (CaZr0.9In0.1O3−x,BaZr0.9Y0.1O3−x, and Ba3Ca1.18Nb1.82O9−x)were used to introduce hydrogen into a vacuum system. A prerequisite was a leak rate below 10−8mbar/s for an assembly consisting of the active tube and a 8YSZ support tube. Mass spectrometry showed that the partial pressure of hydrogen in the vacuum system, pH2, increased linearly with the electric current flowing through the Proton Conductor. All other important partial pressures remained unaffected by this operation. Calculation of throughput during operation of the hydrogen source essentially revealed that the total current, J, is used to transport Protons from the anode to the cathode (tH∼ 1). The number of moles of H2 transported per second is given by J/2F. In essence, the present Proton Conductor tube constitutes a precise, current-controllable device, with a response time of a few seconds only, that delivers ultrahigh-purity hydrogen to a vacuum system.
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Phase transition in the oxygen and Proton Conductor Ba2In2O5 in humid atmospheres below 300°C
Solid State Ionics, 1997Co-Authors: Tilman Schober, J. Friedrich, F. KrugAbstract:The well known oxygen ion and Proton Conductor Ba2In2O5 transforms to a new hydrate-like structure of composition Ba2In2O5·1H2O (labelled β here) when exposed to humidity below 300°C. The water vapor pressure curve over the coexisting α- and β-phases is described by the following thermodynamic parameters: ΔH0=−0.89 eV and ΔS0=−1.27×10−3 eV/K. X-ray powder diffraction also provided evidence for the above phase transition. DTA experiments showed a large endothermic peak at the transition temperature. A tentative quasi-binary phase diagram of the system Ba2In2O5–water vapor is presented. The new Proton-rich phase Ba2In2O5·1H2O is compared with recent high-temperature Proton Conductors.
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Chemical diffusion of water in the high-temperature Proton Conductor Ba3Ca1.18Nb1.82O9-δ
Ionics, 1997Co-Authors: Tilman Schober, J. FriedrichAbstract:Ba3Ca1.18Nb1.82O9-δ (also referred to as BCN18) is a promising high-temperature Proton Conductor. In the dry state it contains an abundant amount of vacancies in the oxygen sublattice. Water may enter the compound occupying the vacancies and supplying Protons to the lattice. The conductivity of these Protons may be used in future applications of high-temperature Proton Conductors as electrolytes for SOFCs and in sensors.
Wenping Sun - One of the best experts on this subject based on the ideXlab platform.
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an easily sintered chemically stable barium zirconate based Proton Conductor for high performance Proton conducting solid oxide fuel cells
Advanced Functional Materials, 2014Co-Authors: Wei Liu, Zhen Shi, Wenping Sun, Mingfei LiuAbstract:Yttrium and indium co-doped barium zirconate is investigated to develop a chemically stable and sintering active Proton Conductor for solid oxide fuel cells (SOFCs). BaZr0.8Y0.2-xInxO3- δ possesses a pure cubic perovskite structure. The sintering activity of BaZr0.8Y0.2-xInxO3- δ increases significantly with In concentration. BaZr0.8Y0.15In0.05O3- δ (BZYI5) exhibits the highest total electrical conductivity among the sintered oxides. BZYI5 also retains high chemical stability against CO2, vapor, and reduction of H2. The good sintering activity, high conductivity, and chemical stability of BZYI5 facilitate the fabrication of durable SOFCs based on a highly conductive BZYI5 electrolyte film by cost-effective ceramic processes. Fully dense BZYI5 electrolyte film is successfully prepared on the anode substrate by a facile drop-coating technique followed by co-firing at 1400 °C for 5 h in air. The BZYI5 film exhibits one of the highest conductivity among the BaZrO3-based electrolyte films with various sintering aids. BZYI5-based single cells output very encouraging and by far the highest peak power density for BaZrO3-based Proton-conducting SOFCs, reaching as high as 379 mW cm−2 at 700 °C. The results demonstrate that Y and In co-doping is an effective strategy for exploring sintering active and chemically stable BaZrO3-based Proton Conductors for high performance Proton-conducting SOFCs.
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samarium and yttrium codoped baceo3 Proton Conductor with improved sinterability and higher electrical conductivity
ACS Applied Materials & Interfaces, 2014Co-Authors: Zhen Shi, Wenping Sun, Zhongtao Wang, Jing Qian, Wei LiuAbstract:Acceptor-doped barium cerate is considered as one of the state-of-the-art high temperature Proton Conductors (HTPCs), and the Proton conductivity of such HTPCs is heavily dependent on the dopant. In this work, a codoping strategy is employed to improve the electrical conductivity and sinterability of BaCeO3-based HTPC. BaCe0.8Sm(x)Y(0.2-x)O(3-δ) (0 ≤ x ≤ 0.2) powders are synthesized by a typical citrate-nitrate combustion method. The XRD and Raman spectra reveal all the compounds have an orthorhombic perovskite structure. The effects of Sm and/or Y doping on the sinterability and electrical conductivity under different atmospheres are carefully investigated. The SEM results of the sintered BaCe0.8Sm(x)Y(0.2-x)O(3-δ) pellets indicate a significant sintering enhancement with increasing Sm concentration. BaCe0.8Sm0.1Y0.1O(3-δ) exhibits the highest electrical conductivity in hydrogen among the BaCe0.8Sm(x)Y(0.2-x)O(3-δ) pellets. Anode-supported BaCe0.8Sm0.1Y0.1O(3-δ) electrolyte membranes are also fabricated via a drop-coating process, and the corresponding single cell exhibits desirable power performance and durability at low temperatures. The results demonstrate that BaCe0.8Sm0.1Y0.1O(3-δ) is a promising Proton Conductor with high conductivity and sufficient sinterability for Proton-conducting solid oxide fuel cells operating at reduced temperatures.
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chemically stable and easily sintered high temperature Proton Conductor bazr0 8in0 2o3 δ for solid oxide fuel cells
Journal of Power Sources, 2013Co-Authors: Wei Liu, Zhen Shi, Wenping Sun, Zhiwen ZhuAbstract:Abstract Barium zirconate-based high-temperature Proton Conductors (HTPCs) exhibit excellent chemical stability in atmospheres containing CO 2 or water vapor. However, such HPTCs haven't been widely used as electrolyte materials for solid oxide fuel cells (SOFCs) due to their poor sintering activity. In this work, indium is selected as a dopant to improve the sintering activity of barium zirconate. BaZr 0.8 In 0.2 O 3− δ (BZI) powders with a pure cubic perovskite structure are synthesized via a typical citric acid–nitrate gel combustion process. The SEM results show that BZI exhibits improved sintering activity compared to the state-of-the-art Proton Conductor BaZr 0.8 Y 0.2 O 3− δ (BZY), and fully dense BZI pellets with increased grain size are obtained after sintered at 1600 °C in air. Moreover, BZI also keeps sufficiently high chemical stability as BZY. The electrical conductivity of BZI under various atmospheres is investigated by electrochemical impedance spectroscopy (EIS) in detail. The total conductivity achieves 1.0 × 10 −3 S cm −1 at 700 °C in wet H 2 (3% H 2 O). Dense BZI electrolyte films are successfully fabricated on the anode substrates by a dry-pressing method after sintered at 1400 °C for 5 h in air. Single cells with dense BZI electrolyte films are also assembled and tested to further evaluate the feasibility of BZI as an electrolyte material for Proton-conducting SOFCs.
Hiroshige Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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extraction and production of hydrogen using high temperature Proton Conductor
Solid State Ionics, 2002Co-Authors: Hiroshige MatsumotoAbstract:Abstract An electrochemical hydrogen pump using the SrCe 0.95 Yb 0.05 O 3− α Proton Conductor has been applied to hydrogen extraction and production. The extraction of hydrogen from dilute hydrogen and synthesis gases, and hydrogen production by water vapor electrolysis are demonstrated. The extraction of hydrogen could be operated with a current efficiency close to unity, while some electronic conduction appeared in the water vapor electrolysis. The introduction of water vapor into the cathode compartment was effective to extend the current density. These results, together with the problems to be solved, are mainly discussed in terms of electrode reactions and ionic transport numbers.
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electrochemical hydrogen pump using a high temperature type Proton Conductor improvement of pumping capacity
Solid State Ionics, 2001Co-Authors: Hiroshige Matsumoto, S Hamajima, Hiroyasu IwaharaAbstract:Abstract In the electrochemical hydrogen pump based on SrCe 0.95 Yb 0.05 O 3− α Proton Conductor cell, effects of water vapor supplied to the cathode and operation temperature on the pumping characteristics were examined. Hydrogen-pumping capacity could be enhanced by increasing water vapor supply to the cathode and by reducing operation temperature within the examined range of 700–900°C. Presence of sufficient water vapor at the cathode would keep the current efficiency of the hydrogen pump.
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electrochemical hydrogen pump using srceo3 based Proton Conductor effect of water vapor at the cathode on the pumping capacity
Journal of The Electrochemical Society, 2001Co-Authors: Hiroshige Matsumoto, S Hamajima, T Yajima, Hiroyasu IwaharaAbstract:Electrochemical pumping of hydrogen through high temperature-type Proton-conducting solid electrolytes has been studied. The effect of water vapor introduced to the cathode on the hydrogen-pumping capacity of the SrCe 0.95 Yb 0.05 O 3-α Proton Conductor cell was investigated in the present study. The pumping capacity of the cell was greatly enhanced when water vapor was introduced to the cathode. The water vapor was consumed at the cathode due to the minor partial oxide ionic conduction in the electrolyte. The role of the water vapor at the cathode in the hydrogen pump is discussed.
