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891.
Engineering the Band Gap States of the Rutile TiO2(110) Surface by Modulating the Active Heteroatom
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Dr. Yaoguang Yu Xu Yang Dr. Yanling Zhao Xiangbin Zhang Dr. Liang An Miaoyan Huang Prof. Gang Chen Prof. Ruiqin Zhang 《Angewandte Chemie (International ed. in English)》2018,57(28):8550-8554
Introducing band gap states to TiO2 photocatalysts is an efficient strategy for expanding the range of accessible energy available in the solar spectrum. However, few approaches are able to introduce band gap states and improve photocatalytic performance simultaneously. Introducing band gap states by creating surface disorder can incapacitate reactivity where unambiguous adsorption sites are a prerequisite. An alternative method for introduction of band gap states is demonstrated in which selected heteroatoms are implanted at preferred surface sites. Theoretical prediction and experimental verification reveal that the implanted heteroatoms not only introduce band gap states without creating surface disorder, but also function as active sites for the CrVI reduction reaction. This promising approach may be applicable to the surfaces of other solar harvesting materials where engineered band gap states could be used to tune photophysical and ‐catalytic properties. 相似文献
892.
Chunqing Ma Dong Shen Ming‐Fai Lo Prof. Chun‐Sing Lee 《Angewandte Chemie (International ed. in English)》2018,57(31):9941-9944
Methylammonium (CH3NH3+) and formamidinium ((NH2)2CH+) based lead iodide perovskites are currently the two commonly used organic–inorganic lead iodide perovskites. There are still no alternative organic cations that can produce perovskites with band gaps spanning the visible spectrum (that is, <1.7 eV) for solar cell applications. Now, a new perovskite using large propane‐1,3‐diammonium cation (1,3‐Pr(NH3)22+) with a chemical structure of (1,3‐Pr(NH3)2)0.5PbI3 is demonstrated. X‐ray diffraction (XRD) shows that the new perovskite exhibits a three‐dimensional tetragonal phase. The band gap of the new perovskite is about 1.6 eV, which is desirable for photovoltaic applications. A (1,3‐Pr(NH3)2)0.5PbI3 perovskite solar cell (PSC) yields a power conversion efficiency (PCE) of 5.1 %. More importantly, this perovskite is composed of a large hydrophobic cation that provides better moisture resistance compared to CH3NH3PbI3 perovskite. 相似文献
893.
Dr. Xin Wang Dr. Junjie He Dr. Benqing Zhou Dr. Youming Zhang Dr. Jiatao Wu Dr. Rui Hu Prof. Liwei Liu Prof. Jun Song Prof. Junle Qu 《Angewandte Chemie (International ed. in English)》2018,57(28):8668-8673
As a highly stable band gap semiconductor, antimonene is an intriguing two‐dimensional (2D) material in optoelectronics. However, its short layer distance and strong binding energy make it challenging to prepare high‐quality large 2D antimonene; therefore, its predicted tunable band gap has not been experimentally confirmed. Now, an approach to prepare smooth and large 2D antimonene with uniform layers that uses a pregrinding and subsequent sonication‐assisted liquid‐phase exfoliation process has been established. Mortar pregrinding provides a shear force along the layer surfaces, forming large, thin antimony plates, which can then easily be exfoliated into smooth, large antimonene, avoiding long sonication times and antimonene destruction. The resulting antimonene also enabled verification of the tunable band gap from 0.8 eV to 1.44 eV. Hole extraction and current enhancement by about 30 % occurred when the antimonene was used as a hole transport layer in perovskite solar cells. 相似文献
894.
《Journal of separation science》2018,41(6):1405-1413
Dextromethorphan is a centrally acting antitussive drug, while its enantiomer levomethorphan is an illicit drug with opioid analgesic effects. As capillary electrophoresis has been proven as an ideal technique for enantiomer analysis, the present study was conducted in order to develop a capillary electrophoresis‐based limit test for levomethorphan. The analytical target profile was defined as a method that should be able to determine levomethorphan with acceptable precision and accuracy at the 0.1 % level. From initial scouting experiments, a dual selector system consisting of sulfated β‐cyclodextrin and methyl‐α‐cyclodextrin was identified. The critical process parameters were evaluated in a fractional factorial resolution IV design followed by a central composite face‐centered design and Monte Carlo simulations for defining the design space of the method. The selected working conditions consisted of a 30/40.2 cm, 50 μm id fused‐silica capillary, 30 mM sodium phosphate buffer, pH 6.5, 16 mg/mL sulfated β‐cyclodextrin, and 14 mg/mL methyl‐α‐cyclodextrin at 20°C and 20 kV. The method was validated according to ICH guideline Q2(R1) and applied to the analysis of a capsule formulation. Furthermore, the apparent binding constants between the enantiomers and the cyclodextrins as well as complex mobilities were determined to understand the migration behavior of the analytes. 相似文献
895.
Enrico Rogora 《Geometriae Dedicata》1997,64(2):157-191
In this paper I give a classification of irreducible projective varieties of dimension less than or equal to four, according to a new classification scheme. No assumption is made about singularities. 相似文献
896.
Brian Forrest 《Proceedings of the American Mathematical Society》1997,125(8):2373-2378
Let be a locally compact group. We will consider amenability and weak amenability for Banach algebras which are quotients of the second dual of the Fourier algebra. In particular, we will show that if is weakly amenable, then has no infinite abelian subgroup.
897.
Andrey Y. Biyanov 《Proceedings of the American Mathematical Society》1997,125(9):2571-2579
The duals of and with respect to disjointness preserving groups are characterized. A. Plessner's result (1929) about the translation group is extended. A Wiener-Young type theorem for disjointness preserving groups is obtained.
898.
为了满足现代通信的要求,论文设计了一种新型圆形共面波导双陷波超宽带天线。天线采用共面波导馈电,实现了良好的超宽频带阻抗匹配。通过在圆形辐射贴片上加载两个C型缝隙,分别在WLAN频段和WiMAX频段处产生陷波,满足了电磁兼容的要求。通过对天线的理论计算结果、仿真结果和实测结果进行比较,吻合较好,通带内天线的回波损耗在-10 dB以下,方向图基本一致,辐射效果良好;阻带内天线增益下降分别为3.2 dB和7.5 dB,实现了较好的陷波抑制辐射作用。 相似文献
899.
在临近空间通信系统中,大气、降雨、闪烁会引起空地链路信道质量的恶化。以临近空间飞艇为通信平台,通过分析Ka频段临近空间通信信道的电波传播特性,重点分析了降雨对信号衰落的影响,在此基础上建立了Ka频段临近空间静止通信信道,以及Ka频段临近空间静止通信信道模型的仿真模型,并在Matlab环境下对Ka频段临近空间静止信道模型的BER性能进行仿真,仿真结果为临近空间链路分析及抗雨衰对策提供理论依据。 相似文献
900.