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991.
Enhanced Catalytic Hydrogen Evolution Reaction in Phosphorene Nanosheet via Cobalt Intercalation 下载免费PDF全文
Searching alternatives to Pt-based catalyst for producing hydrogen via water splitting has gathered enormous attention to develop renewable energy. Phosphorene has been investigated widely for its large surface area, low cost, and high carrier mobility, however, the poor activity in hydrogen evolution reaction (HER) and low conductivity limit its practical application. Herein, on the basis of first-principles calculations, we demonstrate that the catalytic HER in phosphorene can be enhanced significantly with cobalt intercalations. The Co-intercalated phosphorene is metallic with charge transfer from Co atoms to phosphorene, which could enhance the catalytic activity of phosphorene. In addition, the calculated Gibbs free energy of hydrogen adsorption on Co-intercalated phosphorene bilayer is comparable to that on Pt(111) surface, independent of the degree of hydrogen coverage. Our study implies that the Co intercalation provides an effective approach to enhance the catalytic HER inphosphorene. 相似文献
992.
993.
Space-Selective Precipitation of Ba2TiSi2O8 Crystals in Sm3^+-Doped BaO-TiO2-SiO2 Glass by Femtosecond Laser Irradiation 下载免费PDF全文
The ferroelectric crystal Ba2TiSi2O8 with high second-order optical nonlinearity is precipitated in Sm^3+-doped BaO-TiO2-SiO2 glass by a focused 800hm, 250 kHz and 150fs femtosecond laser irradiation. No apparent blue and red emissions are observed at the beginning, while strong blue emission due to second harmonic generation and red emission due to the f-f transitions of Sm^3+ are observed near the focal point of the laser beam after irradiation for 25s. Micro-Raman spectra confirm that Ba2 TiSi2O8 crystalline dots and lines are formed after laser irradiation. The mechanism of the phenomenon is discussed. 相似文献
994.
Stationary Fluid Dynamic Behaviour of V-Shaped Diffuser/Nozzle Elements for Valveless Micropump 下载免费PDF全文
A novel type of V-shaped (isosceles triangle cross-section) diffuser/nozzle element is proposed for use for valveless micropump. Stationary fluid dynamic behaviour of V-shaped diffuser/nozzle elements in a valveless micropump is investigated by experiment and simulation. Both the results agree well with each other when the Reynolds number is higher than 100 and the pressure loss coefficient ratio of micropump nearly always keeps a constant. For a single V-shaped diffuser, the general trends of variation of pressure loss coefficient with opening angle and Reynolds number are opposite in small and large angles. Compared with conical and flat-wall diffusers, V-shaped diffuser shows the smallest pressure loss when the Reynolds number is 200. 相似文献
995.
Blue-to-Orange Tunable Luminescence from Europium Doped Yttrium--Silicon--Oxide--Nitride Phosphors 下载免费PDF全文
Europium-doped yttrium-silicon-oxide-nitride phosphors are synthesized by carbothermal reduction and nitridation method. The crystal structure of the phosphors changed gradually from oxide Y2Si2O7 to nitride YSi3N5 state with increasing dosage of Si3N4 and carbon powder. The Y2Si2O7:Eu phosphor shows a blue emission at 465 nm with 300 nm excitation and a characteristic red emission of Eu^3+ at 612 nm with 230 nm excitation. The YSi3N5:EU phosphor shows a broad emission band centred at 595nm with some sharp peaks of Eu^3+ with 325nm excitation. The absorption of the studied phosphors increases from 450 to 700hm with an increment in nitrogen content. Blue-to-orange tunable luminescence is observed with 390 nm excitation. 相似文献
996.
A theoretical model for tunable Mach--Zehnder interferometers (TMZIs) constructed in a two-dimensional photonic crystal (2D PhC) is proposed. The 2D PhC consists of a square lattice of cylindric air holes in silicon. The TMZI includes two mirrors and two splitters. Light propagates between them employing a self-collimation effect. The two interferometer branches have different path lengths. Parts of the longer branch are infiltrated with a kind of liquid crystal (LC) with ordinary and extraordinary refractive indices 1.522 and 1.706, respectively. The transmission spectra at two TMZI output ports are in the shape of sinusoidal curves and have a uniform peak spacing 0.0017c/a in the frequency range from 0.26c/a to 0.27c/a. When the effective refractive index neff of the liquid crystal is increased from 1.522 to 1.706, the peaks shift to the lower frequencies over 0.0017c/a while the peak spacing is almost kept unchanged. Thus this TMZI can work as a tunable power splitter or an optical switch. For the central operating wavelength around 1550nm, its dimensions are only about tens of micron. Thus this device may be applied to photonic integrated circuits. 相似文献
997.
998.
999.
为满足波面剪切干涉和双细光束干涉曲反射表面非接触精密测量、台阶高度测量以及其他平行分光需要,利用双折射晶体特性,研究并设计了一种单一平板激光平行分束器。当一束激光入射到双折射晶体时,它的2个相互正交的的偏振分量将有不同的折射特性,因此特定晶轴方向和厚度的晶体平行平板可以实现入射光束的平行分束。描述了双折射晶体平行平板的分束原理,推导了分束距离与光轴方向、晶体厚度、入射角的关系,分析了分束距离随主要设计参数的变化规律。采用设计的晶体激光分束器进行了实验测试,验证了分析与实测结果的一致性。 相似文献
1000.
通过一种批量化T/R组件盒体的成型工艺试验和分析,采用压铸工艺,选用合适的压铸铝合金材料、合理的工艺措施,同时解决电磁兼容、散热、三防等关键技术,满足总体设计要求。 相似文献