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91.
92.
《Electrochemistry communications》2007,9(6):1365-1368
Performance of MEMS-based DMFC is low, because graphite-based porous electrodes show poor compatibility with MEMS technology. Nanoimprint technology was adopted in this paper to prepare fine pattern on proton exchange membrane (PEM) in MEMS-based DMFC as a promising alternative to the graphite-based porous electrodes. Micro-convex with the diameter of about 600 nm and the height of 50–70 nm was prepared on Nafion® 117 membrane by the nanoimprint at 130 °C using silicon mold. Thick Pt film (20 nm) was deposited as catalyst directly on the nanoimprinted Nafion® 117 membrane. Then the Pt-coated PEM was sandwiched with micro-channeled silicon plates to form a micro-DMFC. With passively feeding of 1 M methanol solution and air at room temperature, the as-prepared cell had the open circuit voltage (OCV) of 0.74 V and the maximum power density of 0.20 mW/cm2. The measured OCV was higher than those (0.1–0.3 V) of the state-of-the-art MEMS-based DMFC with planar electrode and pure Pt catalyst. 相似文献
93.
利用硝基甲烷还原法在室温条件下得到了纳米Pt粒径可控的担载Pt/γ-Al2O3催化剂, 并利用甲醇重整反应为反应探针考察了Pt粒径与催化反应性能之间的关系, 发现催化反应的性能与担载贵金属颗粒粒径之间存在明显的相关性. 通过透射电镜(TEM)、X射线衍射(XRD)、程序升温还原(TPR)等测试手段对催化剂进行表征, 发现钠米Pt的粒径大小不但影响甲醇重整反应的活性, 同时也影响反应的选择性, 即催化剂的催化性能与担载贵金属粒径之间存在明显的尺度效应. 相似文献
94.
Fa-Kun Zheng A-Qing Wu Yan Li Guo-Cong Guo Ming-Sheng Wang Qiang Li Jin-Shun Huang 《Journal of Molecular Structure》2005,740(1-3):147-151
Three new metal complexes, Cu(4-Hcba)2(4-cba)2(Py)2 (4-Hcba=4-cyanobenzoic acid) 1 and M[H(4-cba)2]2(Py)2 (M=Ni 2, Co 3), have been prepared by the treatment of 4-Hcba with the respective metal nitrate M(NO3)2 (M=Cu, Ni, Co) in the presence of pyridine (Py). Single-crystal X-ray diffraction analyses (3 is isostructural to 2) show that the obtained complexes are of isolated mononuclear and the metal atoms have distorted octahedral coordination environment. Two different types of intramolecular hydrogen bonds exist: asymmetrical O–HO for 1 and symmetrical OHO for 2 and 3. The crystal packing between the molecular complexes is controlled mainly by T-shaped C–Hπ interactions between pyridine and phenyl rings. Preliminary discussions on IR, UV–VIS and fluorescent spectra have also been carried out. 相似文献
95.
Xiaoqing Zeng Maofa Ge Zheng Sun Jiang Bian Dianxun Wang 《Journal of Molecular Structure》2007,840(1-3):59-65
Gaseous nitryl azide N4O2 is generated by the heterogeneous reaction of gaseous ClNO2 with freshly prepared AgN3 at −50 °C. The geometric and electronic structure of the molecule in the gas phase has been characterized by in situ photoelectron spectroscopy (PES) and quantum chemical calculations. The experimental first vertical ionization energy of N4O2 is 11.39 eV, corresponding to the ionization of an electron on the highest occupied molecular orbital (HOMO) {4a″(πnb(N4–N5–N6))}−1. An apparent vibrational spacing of 1600 ± 60 cm−1 (νasO1N2O3) on the second band at 12.52 eV (πnb(O1–N2–O3)) further confirms the preference of energetically stable chain structure in the gas phase. To complement the experimental results, the potential-energy surface of this structurally novel transient molecule is discussed. Both calculations and spectroscopic results suggest that the molecule adopts a trans-planar chain structure, and a five-membered ring decomposition pathway is more favorable. 相似文献
96.
A new Zn(II) complex, [Zn(pyz)(H2O)4]pht (1) (pyz=pyrazine; pht=1,2-benzenedicarboxylate) has been hydrothermally synthesized and characterized. Complex 1 features a novel polar 3D framework with a 1D polycationic chain , between which pht2− dianions are encapsulated via the supramolecular interaction. Its powder SHG is of about three times as large as that of KH2PO4. 相似文献
97.
98.
蒽酮(1)与3,5-二甲氧基苯甲醛(2)在吡啶/哌啶中反应生成10-(3,5-二甲氧基苯甲亚基蒽酮(3); 3经Pd/C催化氢化生成10-(3,5-二甲氧基苄基蒽酮(4); 4与3-甲氧基苄基氯(5)进行相转移催化烷基化反应生成10-(3,5-二甲氧基苄基)-10-(3-甲氧基苄基)蒽酮(6); 6经NaBH4还原生成10-(3,5-二甲氧基苄基)-10-(3-甲氧基苄基)-9(10H)-蒽醇(7); 7在酸催化下发生选择性1,7-脱水反应, 生成高三蝶烯(homotriptycene) (8). 其反应机理可能是7在酸存在下生成正碳离子中间体, 然后选择性地亲电进攻富电荷的3,5-二甲氧基苯基, 而不进攻3-甲氧基苯基. 相似文献
99.
1 INTRODUCTION At present the researches on more efficient solid-state laser materials become more important for the rapid development of diode-laser pumped solid-state laser. More researches have been devoted to the double borate compounds RX3(BO3)4 (R = Y, La, Gd and X = Y, Al, Sc), some of which exhibit good chemical and physical properties[1~10]. The rare earth and alkali-halide double borates M3Ln2(BO3)4 (M = Ca, Sr, Ba and Ln = LaLu and Y) were reported in literatures[11… 相似文献
100.
C60-吡咯烷衍生物的合成及非线性光学性质的研究 总被引:1,自引:0,他引:1
通过富勒烯C60与肌氨酸和有机醛化合物的1,3-偶极环加成反应, 获得了九种含不同有机功能基团的C60吡咯烷衍生物1~9, 用1H NMR, 13C NMR, FTIR, UV-vis和FAB-MS进行了结构表征; 利用皮秒激光光源, 采用z扫描技术测定了分子的三阶非线性超极化率γ(3), 结果显示: 化合物3 (γ(3)=4.14×10-33 esu)具有最大的三阶非线性光学系数, 说明增加噻吩共轭链的长度, 使三阶非线性活性增加; 对具有相同共轭链的C60-噻吩吡咯烷衍生物(2, 5, 1和4), 吸电子取代基减小了三阶光学非线性活性, 给电子基增大了三阶光学非线性活性; 同时发现喹啉环2-位键联(7)比4-位(8)有更好的三阶光学非线性活性. 相似文献