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121.
122.
针对未来光载无线通信所需的高功率、大带宽的光电探测器,提出了一种行波光电二极管级联阵列功率合成电路.先将行波光电二极管级联,再按照阵列式结构将多组级联的光电二极管组合起来,实现射频功率合成,以获得高功率、大带宽的射频信号.采用EDA工具,对该光电转换射频功率合成电路进行仿真模拟.仿真结果表明,该功率合成电路可以有效地将各光电二极管的射频输出信号进行功率合成,功率合成后的信号带宽显著增加,仿真结果与理论分析完全一致.此外,电路分析表明,增加该功率合成电路中的高阻微带线的特性阻抗可以有效提高其输出射频信号的带宽. 相似文献
123.
Molecular Engineering of Push–Pull Porphyrin Dyes for Highly Efficient Dye‐Sensitized Solar Cells: The Role of Benzene Spacers 下载免费PDF全文
Shaik M. Zakeeruddin Shu‐Nung Chang Chi‐Hung Hsieh Chen‐Yu Yeh Michael Grätzel 《Angewandte Chemie (International ed. in English)》2014,53(11):2973-2977
Porphyrins have drawn much attention as sensitizers owing to the large absorption coefficients of their Soret and Q bands in the visible region. In a donor and acceptor zinc porphyrin we applied a new strategy of introducing 2,1,3‐benzothiadiazole (BTD) as a π‐conjugated linker between the anchoring group and the porphyrin chromophore to broaden the absorption spectra to fill the valley between the Soret and Q bands. With this novel approach, we observed 12.75 % power‐conversion efficiency under simulated one‐sun illumination (AM1.5G, 100 mW cm?2). In this study, we showed the importance of introducing the phenyl group as a spacer between the BTD and the zinc porphyrin in achieving high power‐conversion efficiencies. Time‐resolved fluorescence, transient‐photocurrent‐decay, and transient‐photovoltage‐decay measurements were employed to determine the electron‐injection dynamics and the lifetime of the photogenerated charge carriers. 相似文献
124.
A Doping Technique that Suppresses Undesirable H2 Evolution Derived from Overall Water Splitting in the Highly Selective Photocatalytic Conversion of CO2 in and by Water 下载免费PDF全文
Prof. Dr. Kentaro Teramura Zheng Wang Dr. Saburo Hosokawa Prof. Dr. Yoshihisa Sakata Prof. Dr. Tsunehiro Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9906-9909
Photocatalytic conversion of CO2 to reduction products, such as CO, HCOOH, HCHO, CH3OH, and CH4, is one of the most attractive propositions for producing green energy by artificial photosynthesis. Herein, we found that Ga2O3 photocatalysts exhibit high conversion of CO2. Doping of Zn species into Ga2O3 suppresses the H2 evolution derived from overall water splitting and, consequently, Zn‐doped, Ag‐modified Ga2O3 exhibits higher selectivity toward CO evolution than bare, Ag‐modified Ga2O3. We observed stoichiometric amounts of evolved O2 together with CO. Mass spectrometry clarified that the carbon source of the evolved CO is not the residual carbon species on the photocatalyst surface, but the CO2 introduced in the gas phase. Doping of the photocatalyst with Zn is expected to ease the adsorption of CO2 on the catalyst surface. 相似文献
125.
通过掺杂吸收光谱在可见光波段的量子点可提高聚合物对可见光的吸收,因此掺杂CdSe/ZnS核-壳结构量子点(CQDs)能提高聚(3-己基噻吩):[6,6]-苯基-C61-丁酸甲酯(P3HT:PCBM)体异质结太阳电池的能量转换效率.本文研究了CdSe/ZnS量子点在P3HT:PCBM中的不同掺杂比例及其表面配体对太阳电池光伏性能的影响,优化器件ITO(氧化铟锡)/PEDOT:PSS(聚(3,4-乙撑二氧噻吩:聚苯乙烯磺酸)/P3HT:PCBM:(CdSe/ZnS)/Al的能量转换效率达到了3.99%,与相同条件下没有掺杂量子点的参考器件ITO/PEDOT:PSS/P3HT:PCBM/Al相比,其能量转换效率提高了45.1%. 相似文献
126.
ZHANG Jing-Bo LI Pan YANG Hui ZHAO Fei-Yan TANG Guang-Shi SUN Li-Na LIN Yuan 《物理化学学报》2014,30(8):1495-1500
为了提高量子点敏化纳晶薄膜太阳能电池的光电转换效率,我们通过连续在酸和多硫溶液中处理铅片制备了对多硫电解液具有高电催化活性的硫化铅电极.通过电化学阻抗谱测试评价所制备硫化铅电极的催化活性,从而确定制备高效硫化铅电极的最佳条件.以在最佳条件下制备的硫化铅为对电极、CdSe量子点敏化TiO2纳晶薄膜为工作电极和多硫电解液组装成量子点敏化太阳能电池.光电性能测试结果表明所制备的电极具有良好的催化活性和光电转换性能.与已报导的方法相比,新方法大幅度地减少制备过程所需的时间,但却提高了所制备的硫化铅对电极的催化活性.通过X射线衍射和扫描电镜测试表征了硫化铅的生成过程,探讨了催化活性提高的原因. 相似文献
127.
Efficient Solar Cells Sensitized by Porphyrins with an Extended Conjugation Framework and a Carbazole Donor: From Molecular Design to Cosensitization 下载免费PDF全文
Yueqiang Wang Bin Chen Dr. Wenjun Wu Dr. Xin Li Prof. Dr. Weihong Zhu Prof. Dr. He Tian Prof. Dr. Yongshu Xie 《Angewandte Chemie (International ed. in English)》2014,53(40):10779-10783
Porphyrin dyes containing the carbazole electron donor have been designed and optimized by wrapping the porphyrin framework, introducing an additional ethynylene bridge to extend the wavelength range of light absorption, and further suppression of the dye aggregation by introducing additional alkoxy chains. Application of a cosensitization approach results in improved current density (Jsc) and open‐circuit voltage (Voc) values, thus achieving the highest cell efficiency of 10.45 %. This work provides an effective combined strategy of molecular design and cosensitization for developing efficient dye‐sensitized solar cells (DSSCs). In addition, carbazole has been demonstrated to be a promising donor for porphyrin sensitizers. 相似文献
128.
Cover Picture: Development of Double‐Perovskite Compounds as Cathode Materials for Low‐Temperature Solid Oxide Fuel Cells (Angew. Chem. Int. Ed. 48/2014) 下载免费PDF全文
129.
甲烷是一种在自然界中大量存在的原材料,在取代原油和合成重要化工产品等许多领域具有潜在的应用价值. 然而,由于CH4中C-H键的键能特别大(约~4.5 eV),如何实现甲烷的绿色有效转化在化学化工领域仍然是一个挑战. 本文采用密度泛函理论对Co3O4(001)和(011)晶面活化甲烷C-H键的机理进行了理论研究,得到了如下结论:(1) CH4的C-H键在Co3O4晶面的解离具有很高的活性,只需要克服大约1 eV的能垒;(2)与Co2+相连的Co-O离子对是CH4活化的活性位点,其中两个带正负电荷的离子对C-H解离起着协同作用,帮助产生Co-CH3和O-H物种;(3)(011)面的反应活性明显大于(001)面,与实验的观察一致. 本文的计算结果表明,Co3O4纳米晶面对CH4中C-H键的活化表现出明显的晶面效应和结构敏感效应,Co-O离子对活性中心对于活化惰性的C-H键发挥了关键作用. 相似文献
130.
Meng Zhao Dr. Hong-Jie Peng Bo-Quan Li Dr. Xiao Chen Jin Xie Dr. Xinyan Liu Prof. Qiang Zhang Prof. Jia-Qi Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9096-9102
In situ evolution of electrocatalysts is of paramount importance in defining catalytic reactions. Catalysts for aprotic electrochemistry such as lithium–sulfur (Li-S) batteries are the cornerstone to enhance intrinsically sluggish reaction kinetics but the true active phases are often controversial. Herein, we reveal the electrochemical phase evolution of metal-based pre-catalysts (Co4N) in working Li-S batteries that renders highly active electrocatalysts (CoSx). Electrochemical cycling induces the transformation from single-crystalline Co4N to polycrystalline CoSx that are rich in active sites. This transformation propels all-phase polysulfide-involving reactions. Consequently, Co4N enables stable operation of high-rate (10 C, 16.7 mA cm−2) and electrolyte-starved (4.7 μL mgS−1) Li-S batteries. The general concept of electrochemically induced sulfurization is verified by thermodynamic energetics for most of low-valence metal compounds. 相似文献