热处理工艺对CdS微晶掺杂玻璃析晶和二阶非线性光学性能的影响

采用高温熔融法和后期热处理工艺制备了CdS微晶掺杂玻璃.结构分析表明,620 ℃/10 h热处理后CdS微晶颗粒尺寸分布均匀、晶粒发育较好.样品极化前后都观察到了明显的SHG,极化后样品的SH强度有了极大的提高.微晶的尺寸分布和表面状态极大地影响了样品极化前后的SH强度.     

CdS/石墨烯纳米复合材料研究进展

CdS/石墨烯纳米复合材料是一种重要的半导体光催化剂,在可见光下具有很好的催化活性。本文重点介绍了CdS/石墨烯纳米复合材料的制备方法及性能影响因素,并分析了几种常用制备方法的特点及运用效果。本文还介绍了CdS/石墨烯纳米复合材料近年来的应用研究,并对其应用的发展趋势做出了展望。     

Synthesis and photochemical performance of morphology-controlled CdS photocatalysts for hydrogen evolution under visible light

Novel CdS nanomaterials were synthesized by a simple “one-pot” hydrothermal biomolecule-assisted method using glutathione (GSH) as the sulfur source and structure-directing reagent. Various morphologies of CdS photocatalysts, such as solid nanospheres (s-CdS), hollow nanospheres (h-CdS) and nanorods (r-CdS), were obtained by controlling only the hydrothermal temperatures. The X-ray diffraction patterns confirmed that all of the samples were typical hexagonal wurtzite CdS. It was found that the absorption edge of s-CdS was at 465 nm with a greater blue shift compared to that of h-CdS and r-CdS. The photocatalytic activity of s-CdS was superior to that of h-CdS and r-CdS under visible light. Photoluminescence measurements revealed their different photogenerated electron/hole recombination ability, which was in accordance with the order of s-CdS < h-CdS < r-CdS. The excellent photocatalytic activity of s-CdS was ascribed to the small sizes of sub-nanocrystallites, which make it easy for photoinduced electrons and holes on the solid sphere to migrate to the surface and react with water and the sacrificial agent quickly. It was crucial to control the temperature for preparing CdS photocatalysts via hydrothermal methods. The formation mechanism of different morphology might be due to complexation, S-C bond rupture, spherical aggregation and Ostwald ripening processes.     

Optical properties of CdSxTe1−x polycrystalline thin films

Thin films of CdS_xTe_1−x (0≤x≤ 1) have been prepared by vacuum evaporation from solid solutions. Rutherford backscattering spectrometry has been used to determine the thickness of the films, which is in the range 8–50 nm, and x-ray diffraction analysis has been used to determine the phase. The refractive index and extinction coefficient of the films has been calculated from reflectance and transmittance measurements for the wavelength region 250–3200 nm. Polynomial functions are given for each sample, which describe the variation in refractive index and extinction coefficient over the entire wavelength range. Least squares fitting to the absorption spectra revealed that the films all have a direct band gap, although photon energies required for indirect transitions have also been found. CdS_0.8Te_0.2 is found to have the lowest absorption coefficient at energies greater than 2.1 eV.     

XPS analysis of CdS/CuInSe2 heterojunctions

CdS/CuInSe₂ (CIS) heterojunctions were investigated by XPS analysis. An In-excess layer which may form an ordered vacancy compound (OVC) was present at the as-deposited CIS surface and it remained after chemical bath deposition of a CdS layer. The In-excess layer was removed by preferential etching with NH₃ aqueous solution. This result implies that the surface of the as-deposited CIS film was converted from the OVC with n-type conductivity into the CIS with p-type by NH₃ treatment. The conduction band offsets at the CdS/p-CIS and CdS/n-OVC were determined to be 1.0 and 0.3 eV, respectively. The CIS solar cells fabricated with n-OVC surface layer exhibited higher cell efficiencies than those fabricated with p-CIS surface layer.     

Fabrication of vacuum-evaporated SnS/CdS heterojunction for PV applications

SnS/CdS heterojunction is a promising system for the fabrication of thin film solar cells. In our work, thin film SnS/CdS heterojunction was prepared by evaporating CdS and SnS films. The photovoltaic properties of the heterojunction were investigated with posttreatment of the window material treatment by CdCl₂ for grain size enlargement. I–V characteristics in dark and at light were taken and figures of merit were evaluated. The efficiency with and without window layer treatment were about 0.08% and 0.05%, respectively, under 100 mW/cm² intensity. To the best of our knowledge so far there has been no report on vacuum-evaporated SnS-based heterojunction with window material treatment by CdCl₂.     

CdS量子点/CdTe纳米棒光电极制备及其光电性能研究

本文利用化学沉积法和射频溅射法成功实现了CdS量子点/CdTe纳米棒复合光电极的制备。通过X射线粉末衍射(XRD)、扫描电镜(SEM)、紫外-可见吸收光谱(UV-vis)和电化学工作站分别对获得的光电极进行了结构、形貌和光电性能的表征;结果表明,所获得的光电极由CdS量子点和CdTe一维纳米棒组成,其中CdTe纳米棒沿着(111)择优方向定向生长。在不同CdS量子点厚度的光电极的电化学表征结果中,我们发现了由CdS的压电效应引起的新颖的热释电现象,并在25 cycle CdS QDs的光电极测试中获得了最好的结果,开路电压为0.49 V,短路电流为71.09 μA,其I-t曲线的开光比为6。我们在研究过程中还发现了热释电引起的电流反向现象,这一特性对于未来提高光电器件的性能具有重要的意义。     

CdTe/CdS量子点荧光猝灭法测定盐酸西替利嗪

建立一种基于纳米材料的荧光性质测定盐酸西替利嗪含量的新方法,盐酸西替利嗪能使硫化镉包被的碲化镉核壳型量子点(CdTe/CdS QDs)发生规律性的荧光猝灭,研究二者相互作用的最佳条件,从而建立测定盐酸西替利嗪含量的方法。结果表明:盐酸西替利嗪的浓度在0.40~42μg/m L范围内有良好的线性关系(r=0.9992),检测限为2.50×10-2μg/m L,回收率为93.80%~97.00%。结论:此方法简便、快捷、可靠,适用于盐酸西替利嗪的含量测定。     

CdS量子点的合成和指纹检测研究

本工作提出以谷胱甘肽(GSH)为修饰试剂合成了高量子产率的硫化镉量子点,并应用其对非渗透性客体玻璃上的潜在指纹进行显现。结果发现,显现出的指纹清晰可辨,且与背景之间的反差好。该方法具有简便、快速、灵敏、安全、经济等特点。     

Cu掺杂对ZnO量子点光致发光的影响

通过溶液法合成了Cu掺杂ZnO量子点。X射线衍射(XRD)和高分辨电子透射电镜(HRTEM)图像显示Cu掺杂ZnO量子点具有六角纤锌矿结构,晶粒大小为4～5nm。Cu掺杂抑制了ZnO量子点颗粒长大。室温光致发光(PL)谱观察到紫外带边和可见区两个发射峰。随着Cu掺杂浓度的增大,紫外荧光峰位发生缓慢红移,由366nm移到370nm;可见区发射峰位发生蓝移,由525nm移到495nm;同时,两个发射峰强度降低。光谱结果表明:Cu的掺入,一方面抑制表面与O空位有关的缺陷,在495nm出现了与Cu1+有关的发射峰;另一方面,Cu离子掺入ZnO量子点引入一些非辐射中心,降低了自由激子发射。