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991.
Electrolyte effects on the oxygen surface exchange coefficients of strontium-doped lanthanum manganates (LSM) are investigated using electrical conductivity relaxation technique. Introducing electrolytes can significantly reduce the re-equilibration time, demonstrating the substantial promotion in the surface exchange kinetics. The coefficient at 1000 °C increases from 9.00 × 10−5 cm s−1 for pure LSM to 2.45 × 10−4 cm s−1 for LSM coated with yttria-stabilized zirconia, and further increases to 7.92 × 10−4 cm s−1 for LSM with samaria-doped ceria. The nearly one order of magnitude increase in the coefficient demonstrates that introducing electrolytes can effectively increase the electrochemical performance of solid-oxide-fuel-cell cathodes by enhancing the surface exchange reaction in addition to extending the reaction sites. 相似文献
992.
The effects of different types of reducing gas on swelling and iron whisker formation during the reduction of iron oxide compacts were investigated. The compacts sintered in air at 1273 K were reduced at 1173 K in different reducing atmospheres. The results indicated that catastrophic swelling can happen in CO but not when H2 is present in the reducing gas mixture. Scanning electron microscope (SEM) micrographs showed that catastrophic swelling was caused by a large amount of long iron whiskers formed during the reduction. The presence of N2 and CO2 in CO changed the amount of long iron whiskers and its distribution, which determined the extent of swelling. 相似文献
993.
Single-chamber solid oxide fuel cells (SC-SOFCs), which apply fuel-oxidant (air) gas mixture as the atmosphere for both anode and cathode, are receiving many interests recently. This study aims to clarify the mechanism of oxygen reduction and methane oxidization over La0.8Sr0.2MnO3 (LSM) cathode in SC-SOFCs by an electrochemical method in combination with mass spectrometry (MS). Before cathodic polarization, a large polarization resistance (Rp) for oxygen reduction reaction (ORR) was observed and methane did not cause obvious effect on ORR because of the weak adsorption of methane over LSM surface. Cathodic polarization could decrease the Rp obviously due to the in-situ creation of oxygen vacancies; methane likely adsorbed on those oxygen vacancy sites to enhance its effect on ORR. Both the anodic and cathodic polarizations significantly increased the rate of methane oxidation over LSM electrode; in particular, the pumped oxygen anion was highly active for methane oxidation. 相似文献
994.
Anode-supported cone-shaped tubular solid oxide fuel cells (SOFCs) are successfully fabricated by a phase inversion method. During processing, the two opposite sides of each cone-shaped anode tube are in different conditions--one side is in contact with coagulant (the corresponding surface is named as “W-surface”), while the other is isolated from coagulate (I-surface). Single SOFCs are made with YSZ electrolyte membrane coated on either W-surface or I-surface. Compared to the cell with YSZ membrane on W-surface, the cell on I-surface exhibits better performance, giving a maximum power density of 350 mW cm−2 at 800 °C, using wet hydrogen as fuel and ambient air as oxidant. AC impedance test results are consistent with the performance. The sectional and surface structures of the SOFCs were examined by SEM and the relationship between SOFC performance and anode structure is analyzed. Structure of anodes fabricated at different phase inversion temperature is also investigated. 相似文献
995.
Sea-Fue Wang Yung-Fu HsuHsi-Chuan Lu Shih-Chieh LoChieh-Sheng Cheng 《International Journal of Hydrogen Energy》2012
In this study, the chemical and thermal stabilities of eleven B2O3-free SiO2–Al2O3–SrO–La2O3–ZnO–TiO2 glasses were investigated, and the adhesion and sealing properties of the glasses with respect to Gd0.2Ce0.8O2−δ (GDC) electrolyte and SUS 430 stainless steel (SUS430) were evaluated for use in intermediate temperature solid oxide fuel cells (ITSOFCs). It was found that the major crystallites formed in the glasses were initiated during the joining process at 950 °C, and only slight changes were observed in the intensity of crystallite peaks for the glasses subsequently soaked at 700 °C for 200 h. Experiments on the glass sandwiched with GDC electrolyte and SUS430 indicated that the SALSTi11 and SALSZT10 glasses provided good adhesion along the interfaces after heat treatment. According to the results of leakage test, the seals with the SALSTi11 and SALSZT10 glasses at 700 °C for a duration of 500 h showed good thermal stability with low leak rates of 0.007 and 0.003 sccm/cm at 0.5 psi, respectively. This property indicates a highly promising long-term thermal stability qualifying the sealing materials for ITSOFC applications. 相似文献
996.
《分离科学与技术》2012,47(9-10):2840-2858
Abstract In previous studies, we have examined using sodium permanganate for selectively oxidizing and removing chromium from washed Hanford tank sludges. The conclusion from the previous work was that contact with sodium permanganate in a minimally caustic solution, i.e., 0.1 to 0.25 M [OH–] initially, provided maximum Cr dissolution while minimizing concomitant Pu dissolution. This report describes work focused on developing simulants to be used in pilot scale oxidative leaching tests; developing methods for monitoring chromium oxidation by permanganate; and identifying the Cr and Mn materials formed during the oxidative leaching process. The impact of such variables as the Cr compound used, agitation rate, temperature, hydroxide concentration, and initial MnO4 ?:Cr ratio on the rate and extent of chromate formation were examined. 相似文献
997.
Antoine Debuigne Marie HurtgenChristophe Detrembleur Christine JérômeChristopher Barner-Kowollik Thomas Junkers 《Progress in Polymer Science》2012,37(7):1004-1030
The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system. 相似文献
998.
Tunable Spectrum Selectivity for Multiphoton Absorption with Enhanced Visible Light Trapping in ZnO Nanorods 下载免费PDF全文
Kok Hong Tan Fang Sheng Lim Alfred Zhen Yang Toh Xia‐Xi Zheng Chang Fu Dee Burhanuddin Yeop Majlis Siang‐Piao Chai Wei Sea Chang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(20)
Observation of visible light trapping in zinc oxide (ZnO) nanorods (NRs) correlated to the optical and photoelectrochemical properties is reported. In this study, ZnO NR diameter and c‐axis length respond primarily at two different regions, UV and visible light, respectively. ZnO NR diameter exhibits UV absorption where large ZnO NR diameter area increases light absorption ability leading to high efficient electron–hole pair separation. On the other hand, ZnO NR c‐axis length has a dominant effect in visible light resulting from a multiphoton absorption mechanism due to light reflection and trapping behavior in the free space between adjacent ZnO NRs. Furthermore, oxygen vacancies and defects in ZnO NRs are associated with the broad visible emission band of different energy levels also highlighting the possibility of the multiphoton absorption mechanism. It is demonstrated that the minimum average of ZnO NR c‐axis length must satisfy the linear regression model of Z p,min = 6.31d to initiate the multiphoton absorption mechanism under visible light. This work indicates the broadening of absorption spectrum from UV to visible light region by incorporating a controllable diameter and c‐axis length on vertically aligned ZnO NRs, which is important in optimizing the design and functionality of electronic devices based on light absorption mechanism. 相似文献
999.
Chiranjeeva Rao Seela B. Ravisankar 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(21):2564-2571
This work investigates the suspension duration of the nanosized multiwalled carbon nanotubes (MWCNT) and aluminum oxide (Al2O3) in B20, B50 and B70 blends of Jatropha Methyl ester. The MWCNT and aluminum oxide (Al2O3) are added to the fuel blends in the proportions of 50 and 100 pmm separately by ultra sonication. The prepared fuel samples are characterized, and turbidity analysis was done to find the stability rate of nano-additives. The outcomes reveal the maximum stability rate for MWCNT and Al2O3 as 83.3% and 87.03%, respectively, with 50ppm in B20 over a period of eighteen days. A considerable drop in suspension was observed with the 100 ppm MWCNT and Al2O3 biodiesel blends. 相似文献
1000.
为进一步提升护岸材料对面源污染物的净化能力,采用骨料交联法制备了具有较高透水率的多孔生态砌块,研究骨料粒径与砌块透水率的关系,并采用动水挂膜法对不同透水率的生态砌块进行反硝化细菌表面负载,在此基础上,研究所制备的不同骨料粒径的生态砌块的透水率、比表面积等对水体中硝态氮去除率的耦合效应。结果表明:在相同孔隙率条件下生态砌块的透水率随比表面积的增加而降低,且随着骨料粒径的增大而提高;生态砌块对水体中硝态氮的去除率随透水率的增加呈现先增大再减小的趋势,其中骨料粒径为7~11 mm,透水率为6.6 m L/(s.cm~2)的多孔生态砌块对硝态氮的去除率可达90.3%。 相似文献