共查询到20条相似文献,搜索用时 31 毫秒
1.
The layered SmBa0.5Sr0.5Co2O5+δ (SBSC) perovskite oxide is synthesized by the Pechini method and investigated as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). A laboratory-sized Sm0.2Ce0.8O1.9 (SDC)-based tri-layer cell of NiO–SDC/SDC/SBSC is operated from 500 to 700 °C fed with humidified H2 (3% H2O) as a fuel and the static ambient air as oxidant. A maximum power density of 1147 mW cm−2 is achieved at 700 °C. The interfacial polarization resistance is as low as 1.01, 0.38, 0.16, 0.06 and 0.03 Ω cm2 at 500, 550, 600, 650 and 700 °C, respectively. The experimental results indicate that SBSC is a very promising cathode material for IT-SOFCs. 相似文献
2.
Ling Zhao Beibei He Bin Lin Hanping Ding Songlin Wang Yihan Ling Ranran Peng Guangyao Meng Xingqin Liu 《Journal of power sources》2009,194(2):835-837
A dense BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte is fabricated on a porous anode by in situ drop-coating method which can lead to extremely thin electrolyte membrane (10 μm in thickness). The layered perovskite structure oxide PrBaCo2O5+δ (PBCO) is synthesized by auto ignition process and initially examined as a cathode for proton-conducting IT-SOFCs. The electrical conductivity of PrBaCo2O5+δ (PBCO) reaches the general required value for the electrical conductivity of cathode absolutely. The single cell, consisting of PrBaCo2O5+δ (PBCO)/BaZr0.1Ce0.7Y0.2O3−δ (BZCY)/NiO-BaZr0.1Ce0.7Y0.2O3−δ (BZCY) structure, is assembled and tested from 600 to 700 °C with humidified hydrogen (3% H2O) as the fuel and air as the oxidant. An open-circuit potential of 1.01 V and a maximum power density of 545 mW cm−2 at 700 °C are obtained for the single cell, and a low polarization resistance of the electrodes of 0.15 Ω cm2 is achieved at 700 °C. 相似文献
3.
Hongxia Gu Yao Zheng Ran Ran Zongping Shao Wanqin Jin Nanping Xu Jeongmin Ahn 《Journal of power sources》2008,183(2):471-478
Perovskite-type La0.8Sr0.2ScyMn1−yO3−δ oxides (LSSMy, y = 0.0–0.2) were synthesized and investigated as cathodes for solid-oxide fuel cells (SOFCs) containing a stabilized zirconia electrolyte. The introduction of Sc3+ into the B-site of La0.8Sr0.2MnO3−δ (LSM) led to a decrease in the oxides’ thermal expansion coefficients and electrical conductivities. Among the various LSSMy oxides tested, LSSM0.05 possessed the smallest area-specific cathodic polarization resistance, as a result of the suppressive effect of Sc3+ on surface SrO segregation and the optimization of the concentration of surface oxygen vacancies. At 850 °C, it was only 0.094 Ω cm2 after a current passage of 400 mA cm−2 for 30 min, significantly lower than that of LSM (0.25 Ω cm2). An anode-supported cell with a LSSM0.05 cathode demonstrated a peak power density of 1300 mW cm−2 at 850 °C. The corresponding value for the cell with LSM cathode was 450 mW cm−2 under the same conditions. The LSSM0.05 oxide may potentially be a good cathode material for IT-SOFCs containing doped zirconia electrolytes. 相似文献
4.
Jinping Liang Qingshan Zhu Zhaohui Xie Wenlai Huang Chaoquan Hu 《Journal of power sources》2009,194(2):640-645
Nanocrystalline Ce0.8Gd0.2O1.9 (GDC20) powder was synthesized by ammonia co-precipitation combined with supercritical ethanol drying route, followed by characterizations with TG/DSC, XRD, BET, HR-TEM, and FESEM techniques. After calcination at 600 °C, the powder has a high specific surface area of 146.5 m2 g−1 and an average crystal size of 5 nm without hard-agglomeration. The nano-GDC powder showed excellent sinterability, where by pressureless sintering at 900 °C for 4 h, the relative density of more than 98% and average grain size of 84 nm have been attained, which is attributed to the powder's ultrafine nanocrystal size, weak agglomeration and high homogeneity. Investigations indicate that in the initial sintering stage, grain growth behavior is mainly controlled by volume diffusion mechanism with an activation energy of 5.4 eV. 相似文献
5.
A. Subrahmanyam C. Suresh Kumar K. Muthu Karuppasamy 《Solar Energy Materials & Solar Cells》2007,91(1):62-66
In the present investigation, the electrochromic properties of a fast protonic solid state device: NiOx/Ta2O5/WO3−x prepared at room temperature (300 K) is reported. The non-stoichiometric tungsten oxide thin film is prepared by reactive DC magnetron sputtering technique on ITO coated glass; the oxides of tantalum (300 nm) and nickel (100 nm) are prepared by electron beam evaporation. This proton device has a coloration efficiency of 82.4 cm2/C and coloration and bleaching time of 6 and 5 s, respectively, and a transmittance variation of 60%. The work function of WO3−x thin films by Kelvin probe in uncolored and colored states are 4.73 and 4.30 eV, respectively. 相似文献
6.
Masaru Tsuchiya Bo-Kuai Lai Alex C. Johnson Shriram Ramanathan 《Journal of power sources》2010,195(4):541-1000
We report on the synthesis and functional properties of nanoscale (50 nm) dense Y-doped zirconia (YDZ) electrolyte thin films by photon-assisted oxidation of Zr–Y precursor alloy thin films. Crystalline zirconia films with grain size of 5 nm were successfully grown at room temperature by oxidation under ultra-violet (UV) photon irradiation. Microstructure of the films was characterized by transmission electron microscopy. The electrochemical conductivity of UV grown YDZ electrolytes was investigated over a broad range of temperatures using Pt electrodes as a function of yttria doping concentration. The slightly lower electrical conductivity in UV grown films at intermediate temperature range (400–550 °C) is consistent with previous reports on oxygen defect annihilation under photo-excitation. Micro-fuel cells utilizing such ultra-thin YDZ membranes yielded 12 mW cm−2 power density at 550 °C. The results are of potential relevance in advancing low temperature ultra-thin oxide membrane synthesis for energy applications. 相似文献
7.
Melanie Kuhn Teko W. Napporn Michel Meunier Srikar Vengallatore Daniel Therriault 《Journal of power sources》2009,194(2):941-949
Single-chamber solid oxide fuel cells with coplanar microelectrodes were operated in methane–air mixtures (Rmix = 2) at 700 °C. The performance of cells with one pair of NiO–YSZ (yttria stabilized zirconia) anode and (La0.8Sr0.2)0.98MnO3–YSZ cathode, arranged parallel on a YSZ electrolyte substrate, was found to be significantly dependent on the electrode width. For an interelectrode gap of 250 μm, cells with average electrode widths exceeding 850 μm could establish a stable open circuit voltage (OCV) of 0.8 V, while those with widths less than 550 μm could not establish any OCV. In the intermediate range, the cells exhibited significant fluctuations in voltage and power under our testing conditions. This behavior suggests that a lower limit to electrode dimensions exists for cells with single electrode pairs, below which neither a stable difference in oxygen partial pressure, nor an OCV, can be established. Conversely, increasing the electrode width imposes a penalty in the form of an increase in the cell resistance. However, both size limits can be circumvented by employing multiple pairs of microscale electrodes in an interdigitated configuration. 相似文献
8.
TiO2 thin films as protective material for transparent-conducting oxides used in Si thin film solar cells 总被引:1,自引:0,他引:1
H. Natsuhara K. Matsumoto N. Yoshida T. Itoh S. Nonomura M. Fukawa K. Sato 《Solar Energy Materials & Solar Cells》2006,90(17):2867-2880
Nb-doped TiO2 films have been fabricated by RF magnetron sputtering as protective material for transparent-conducting oxide (TCO) films used in Si thin film solar cells. It is found that TiO2 has higher resistance against hydrogen radical exposure, utilizing the hot-wire CVD (catalytic CVD) apparatus, compared with SnO2 and ZnO. Further, the minimum thickness of TiO2 film as protective material for TCO was experimentally investigated. Electrical conductivity of TiO2 in the as-deposited film is found to be 10−6 S/cm due to the Nb doping. Higher conductivity of 10−2 S/cm is achieved in thermally annealed films. Nitrogen treatments of Nb-doped TiO2 film have been also performed for improvements of optical and electric properties of the film. The electrical conductivity becomes 4.5×10−2 S/cm by N2 annealing of TiO2 films at 500 °C for 30 min. It is found that the refractive index n of Nb-doped TiO2 films can be controlled by nitrogen doping (from n=2.2 to 2.5 at λ = 550 nm) using N2 as a reactive gas. The controllability of n implies a better optical matching at the TCO/p-layer interface in Si thin film solar cells. 相似文献
9.
Dengyuan Song Eun-Chel Cho Gavin Conibeer Chris Flynn Yidan Huang Martin A. Green 《Solar Energy Materials & Solar Cells》2008,92(4):474-481
Thin films of Si nanocrystals (Si NCs) embedded in a silicon carbide (SiC) matrix (Si-NC:SiC) were prepared by alternating deposition of Si-rich silicon carbide (Si1−xCx) and near-stoichiometric SiC mutilayers (Si1−xCx/SiC) using magnetron cosputtering followed by a post-deposition anneal. Transmission electron microscopy and Raman spectroscopy revealed that the Si NCs were clearly established, with sizes in the range of 3–5 nm. Optical studies showed an increase in the optical band gap after annealing from 1.4 eV (as-deposited) to 2.0 eV (annealed at 1100 °C). P-type Si-NC:SiC/n-type crystalline silicon (c-Si) heterojunction (HJ) devices were fabricated and their electrical and photovoltaic properties were characterized. The diode showed a good rectification ratio of 1.0×104 at the bias voltage of ±1.0 V at 298 K. The diode ideality factor and junction built-in potential deduced from current–voltage and capacitance–voltage plots are 1.24 and 0.72 V, respectively. Illuminated I–V properties showed that the 1-sun open-circuit voltage, short-circuit current density and fill factor of a typical HJ solar cell were 463 mV, 19 mA/cm2 and 53%, respectively. The external quantum efficiency and internal quantum efficiency showed a higher blue response than that of a conventional c-Si homojunction solar cell. Factors limiting the cell's performance are discussed. 相似文献
10.
Alexander S. Bondarenko Weihua Zhou Henny J.M. Bouwmeester 《Journal of power sources》2009,194(2):843-846
Novel thin film composite electrolyte membranes, prepared by dispersion of nano-sized SiO2 particles in the solid acid compound KH(PO3H), can be operated under both oxidizing and reducing conditions. Long-term stable proton conductivity is observed at 140 °C, i.e., slightly above the superprotonic phase transition temperature of KH(PO3H), under conditions of relatively low humidification (pH2O ≈ 0.02 atm). 相似文献
11.
P.K. Ghosh U.N. Maiti Sk.F. Ahmed K.K. Chattopadhyay 《Solar Energy Materials & Solar Cells》2006,90(16):2616-2629
Transparent conducting Cd1−xSnxS thin films have been synthesized by radio frequency magnetron sputtering technique on glass and Si substrates for various tin concentrations in the films. X-ray diffraction studies showed broadening of peaks due to smaller crystal size of the Cd1−xSnxS films, and SEM micrographs showed fine particles with average size of 100 nm. Sn concentration in the films was varied from 0% to 12.6% as determined from energy-dispersive X-ray analysis. The room-temperature electrical conductivity was found to vary from 8.086 to 939.7 S cm−1 and corresponding activation energy varied from 0.226 to 0.076 eV. The optimum Sn concentration for obtaining maximum conductivity was found to be 9.3%. The corresponding electrical conductivity was found to be 939.7 S cm−1, and the mobility 49.7 cm2 V−1 s−1. Hall measurement showed very high carrier concentrations in the films lying in the range of 8.0218×1018–1.7225×1020 cm−3. The conducting Cd1−xSnxS thin films also showed good field emission properties with a turn on field 4.74–7.86 V μm−1 with variation of electrode distance 60–100 μm. UV–Vis–NIR spectrophotometric studies of the films showed not needed the optical band gap energy increased from 2.62 to 2.80 eV with increase of Sn concentration in the range 0–12.6%. The optical band gap was Burstein–Moss shifted, and the corresponding carrier concentration obtained from the shift also well matched with that obtained from Hall measurement. 相似文献
12.
Hydrothermal decomposition of permanganate, conducted in a range of pH-controlled solutions (from strongly acidic to strongly basic), is used to prepare manganese dioxides that are well-suited for use as supercapacitor electrode materials. While permanganate is thermodynamically unstable, the kinetics of its decomposition in an aqueous environment are very slow, until the temperature is raised to 200 °C. Although the resultant materials are relatively crystalline and have low total pore volume, their prominent meso-porosity leads to good electrochemical performance. Best behaviour is obtained for material from permanganate decomposition in 0.01 M H2SO4 solution, for which composite electrodes (150 μm thick) yield 150 F g−1 at 5 mV s−1 in a 9 M KOH electrolyte. 相似文献
13.
Tumpa Dutta Amit Kumar Das Debabrata Das 《International Journal of Hydrogen Energy》2009,34(17):7530-7537
Fe-hydrogenase from Enterobacter cloacae IIT-BT08 was purified 1284 fold with specific activity of 335 μmol H2/min/mg protein for hydrogen evolution using reduced methyl viologen as an electron-donor at 25 °C. The molecular weight of the monomeric enzyme was determined to be 51 kDa by MALDI-ToF mass spectrometry. The PI of the enzyme was 5.6 displaying its acidic nature. The optimal temperature and pH for hydrogen evolution was 37 °C and 7–7.2 respectively. The affinity constant, Km for reduced methyl viologen was 0.57 ± 0.03 mM and that of reduced ferredoxin was 0.72 ± 0.04 μM. The enzyme contained 11.47 gm-atom Fe/mol of Fe-hydrogenase. Electron paramagnetic resonance analysis ascertained the existence of iron molecules as [4Fe–4S] clusters. The internal amino acid sequences of trypsin digested peptides of hydrogenase as determined by ESI MS/MS Q-ToF showed 80-87% identities with the respective sequences of Clostridium sp. and Trichomonas sp. hydrogenase. 相似文献
14.
G. K. R. Senadeera P. V. V. Jayaweera V. P. S. Perera K. Tennakone 《Solar Energy Materials & Solar Cells》2002,73(1):208
A solid-state dye-sensitized photovoltaic cell consisting of vacuum deposited pentacene onto ruthenium dye-coated TiO2 electrode doped with iodine was fabricated. Cell delivers a short-circuit current of 3.6 mA cm−2 and an open-circuit voltage of 415 mV at 100 mW cm–2 (1.5 air mass). The efficiency and the fill factors of the above cell are 0.8% and 0.5%, respectively. Studies of the photocurrent action spectra showed that the dye is mainly responsible for this photocurrent generation. Preliminary results under extended illumination suggested that “long term” stability of the cell is promising. 相似文献
15.
Using noble gas argon as a diluent of SiH4 in RF glow discharge, undoped μc-Si:H thin films have been developed at a low power density of 30 mW/cm2. It has been found that the gas pressure is a critical factor for the growth of μc-Si:H films. Undoped μc-Si:H films having σD10−6 S/cm and ΔE<0.57 eV have been obtained at and above a critical pressure of 0.8 Torr. When the RF power density is increased to 90 mW/cm2, a more crystalline as well as highly conducting (σD10−4 S/cm) μc-Si:H film has been achieved at a deposition rate of 30 Å/min, which is much higher than that attained from H2-diluted SiH4 plasma, by conventional approach. The crystallinity of the films has been identified by the sharp Raman peak at 520 cm−1 and a large number of micrograins in the TEM micrographs. The metastable state of Ar, denoted as Ar*, plays the crucial role in inducing microcrystallisation by transferring its de-excitation energy at the surface of the growing film. A mechanism has been proposed to explain the dependence of the formation of μc-Si:H film on the working gas pressure in the plasma. 相似文献
16.
Jeremy J. Pietron Arnold M. Stux Ratonya S. Compton Debra R. Rolison 《Solar Energy Materials & Solar Cells》2007,91(12):1066-1074
We describe the fabrication and performance of dye-sensitized photoanodes derived from TiO2 aerogel. Nanocrystalline titania aerogel is a bicontinuous, nanostructured pore–solid architecture featuring specific surface areas of 85–150 m2/g and a continuous mesoporous network, allowing chemisorption of high concentrations of sensitizing dye and rapid mass-transport of electron-transfer mediators. Considerable design and processing flexibility arises with aerogels because the continuous pore–solid networks are fixed by the supercritical drying process, allowing the creation of multifunctional, nanostructured films of single or multiple layers. Titania aerogels can be processed as powders and deposited as nearly opaque films from 2 μm to >35-μm thick while retaining their bicontinuous nanoscale networks. Two-layer, 30-μm-thick TiO2 aerogel films yield incident photon-to-electron conversion efficiency (IPCE) values of 85% in the 500–600 nm range and 52% at 700 nm with N719 as a sensitizing dye and after correcting for transmittance of the 3.2-mm-thick FTO-coated glass substrates at these wavelengths. 相似文献
17.
This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO2 and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 °C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, ΔTp1, and that in the condenser, ΔTp2 are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was 5.9 years at most, and would be reduced to 3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 $/kWe, and the cost of electricity is estimated to be 0.34–0.37 CNY/kWh (0.04 $/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO2 emissions at that. 相似文献
18.
A series of cobalt-free and low cost BaCexFe1−xO3−δ (x = 0.15, 0.50, 0.85) materials are successful synthesized and used as the cathode materials for proton-conducting solid oxide fuel cells (SOFCs). The single cell, consisting of a BaZr0.1Ce0.7Y0.2O3−δ (BZCY7)-NiO anode substrate, a BZCY7 anode functional layer, a BZCY7 electrolyte membrane and a BaCexFe1−xO3−δ cathode layer, is assembled and tested from 600 to 700 °C with humidified hydrogen (3% H2O) as the fuel and the static air as the oxidant. Within all the cathode materials above, the cathode BaCe0.5Fe0.5O3−δ shows the highest cell performance which could obtain an open-circuit potential of 0.99 V and a maximum power density of 395 mW cm−2 at 700 °C. The results indicate that the Fe-doped barium cerates can be promising cathodes for proton-conducting SOFCs. 相似文献
19.
F. Sauvage V. Bodenez H. Vezin M. Morcrette J.-M. Tarascon K.R. Poeppelmeier 《Journal of power sources》2010,195(4):1235-10757
We investigated the effect of inserting lithium into Ag2V4O11 (-SVO) on the structure, electronic properties and redox committed by combining in situ XRD measurements, ESR spectroscopy and 4 probes DC conductivity coupled with thermopower measurements. The electrochemical discharge occurs in three consecutive steps above 2 V (vs. Li+/Li). The first one, between 0 < x < 0.7 in Lix-SVO, has been ascribed to the V5+ reduction through a solid solution mechanism. This reduction competes with a Li+/Ag+ displacement reaction which leads to a structural collapse owing to the ionic radii mismatch between the withdrawn Ag+ and the inserted Li+. The silver reduction progresses continuously with two different slopes along two composition–potential plateaus at 2.81 V and 2.55 V. Finally, the reduction continues until we obtain an amorphous structure with V4+ and a of V3+. Although, the silver re-enters the structure during the subsequent recharge, the original structure is not recovered. The reduction of silver forming silver metal nano-clusters acts to increase the electronic conductivity from 3.8 × 10−5 S cm−1 to 1.4 × 10−3 S cm−1. In complement to this study, we also report on a low temperature hydro-(solvo)-thermal approach using HF(aq) as a mineralizer, which enables the synthesis of nano-sized -SVO particles that exhibit superior electrochemical performances compared to conventional particles synthesized by solid-state reaction. 相似文献
20.
Thermal decomposition of LiAlH4 chemically mixed with Lithium amide and transition metal chlorides 总被引:1,自引:0,他引:1
Mehraj-ud-din Naik Sami-ullah Rather Chang Su So Sang Woon Hwang Ae Rhan Kim Kee Suk Nahm 《International Journal of Hydrogen Energy》2009,34(21):8937-8943
Thermogravimetric analysis of LiAlH4 chemically mixed with different additives is reported for the application of hydrogen storage. Here, we illustrated the dehydrogenation properties of combined LiAlH4/LiNH2 (2:1) mixture and LiAlH4 wet-doped with different transition metals (Sc, Ti, and V) in their chloride forms. Thermal gravimetric analysis of LiAlH4/LiNH2 system released 7.9 wt.% of hydrogen in three decomposition steps at temperatures between 75 and 280 °C under a heating ramp of 5 °C min−1. The LiAlH4 doped with transition metals showed the decrease of decomposition temperature down to 30–40 °C for both 1st and 2nd dehydrogenation steps as compared to as-received LiAlH4. The catalytic activity in lowering the dehydrogenation temperature of LiAlH4 doped with transition metals increases in the order of pure LiAlH4 < V < Ti < Sc. The X-ray diffraction analysis, field emission scanning electron microscopy, and Fourier transformation infra-red spectroscopy techniques were carried out in support of the thermogravimetric results. 相似文献