CdSe和ZnO量子点的拉曼光谱研究

本文介绍了用拉曼光谱研究CdSe和ZnO两种Ⅱ Ⅳ族量子点材料的结果,对拉曼峰进行了指认。观察到的光学声子峰位的移动被认为是由量子限制效应引起。     

Photocatalytic Synthesis of Composite CdSe/CdS Nanoparticles

We have shown that CdSe/CdS nanocomposites can be obtained in a photocatalytic reaction with participation of CdS nanoparticles from sodium selenosulfate. We have studied the kinetic characteristics of this process in detail and have shown that its most likely mechanism includes a step involving reaction between SeSO^3/2− anions and electrons generated in the conduction band of the CdS nanoparticles during irradiation and stabilized in traps on the semiconductor surface.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 3, pp. 171–175, May–June, 2005.     

Photoelectrochemical behavior of coupled SnO2|CdSe nanocrystalline semiconductor films

A photoelectrochemical cell with a coupled SnO₂|CdSe nanocrystalline semiconductor electrode has been prepared by sequential deposition of SnO₂ and CdSe films onto an optically transparent electrode (OTE), and its photoelectrochemical behavior has been studied. The results show that the coupling of CdSe with SnO₂ leads to an improvement in the performance of OTE|SnO₂|CdSe over OTE|CdSe cells in terms of increased incident photon-to-current conversion efficiency, increased stability and smaller reversal of current. The favorable positioning of the energy bands of SnO₂ and CdSe is responsible for the above observations. Various photoelectrochemical parameters of the OTE|SnO₂|CdSe cell obtained for an incident light power of 0.31 mW cm⁻² at 470nm, are as follows: I_sc ≈ 25–30 μA cm⁻², V_oc ≈ 0.5–0.6 V, ƒƒ = 0.47 and a power conversion efficiency of about 2.25%.     

Preparation and characterization of high-specific-surface-area activated carbons from K2CO3-treated waste polyurethane

An activated carbon with high specific surface area was prepared from polyurethane foam by chemical activation with K2CO3 and the influences of carbonization temperature and impregnation ratio on the pore structure of the prepared activated carbon were investigated. It was found that the specific surface area of the activated carbon was at a maximum value (about 2800 m(2)/g) at a carbonization temperature of 1073 K and at an impregnation ratio of 1.0. It was concluded that the polyurethane foam structure was modified during impregnation by K2CO3, K2CO3 promoted charring during carbonization, and then the weight loss behavior was changed below 700 and above 1000 K, carbon in the char was consumed by K2CO3 reduction, and this led to the high specific surface area. The prepared activated carbon had a very sharp micropore size distribution, compared with the commercial activated carbon having high specific surface area. The amounts of three organic vapors (benzene, acetone, and octane) adsorbed on the prepared activated carbons was much larger than those on the traditional coconut shell AC and the same as those on the commercial activated carbon except for octane. We surmised that the high specific surface area was due to the modification of the carbonization behavior of polyurethane foam by K2CO3.     

发光反应型有机铵分子与CdSe纳米晶的组装

用巯基乙酸做稳定剂制备了水溶性CdSe纳米颗粒, 用十六烷基三甲基溴化铵(HTAB)、发光性(4-甲氧基均二苯乙烯基)二甲基乙基溴化铵 (MODAB)及末端含有双键的(4-甲基丙烯酰氧基均二苯乙烯基)二甲基乙基溴化铵(MSDAB)对该CdSe纳米颗粒进行了混合组装.通过改变三种有机分子的比例可以调控所得组装体的溶解性、聚合性及其发光性质.实验结果表明,当HTAB:MODAB:MSDAB=1:5.98～5.90:0.02～0.10(摩尔比)时,所得组装体具有较好的聚合性、溶解性和荧光性质.     

CdSe量子点的光物理性质研究与荧光杂化纤维的制备

半导体纳米晶体(NCs)具有良好的光稳定性,广泛的发射持久性和高消光系数,在过去几年被广泛研究报道,其中,硒化镉半导体纳米晶体(CdSe NCs)被广泛用于电子照明、太阳能发电、光电传感等领域.然而CdSe NCs的电学、热力学和光物理性质具有较强的尺寸依赖性,在传统的制备方法及应用中容易出现晶体表面缺陷和悬空键以及较...     

用CdSe/ZnS量子点提高体异质结有机太阳电池的效率

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%.     

CdSe晶体倍频光学参数及元件加工研究

对红外非线性光学晶体CdSe的倍频光学参数及其元件加工进行了研究.根据非线性光学原理和折射率色散关系,从理论上计算出CdSe晶体的有效非线性系数和倍频元件相位匹配角与基频光波长(5.5～10.0 μm)的调谐特性曲线,从实验上探索到一种通过解理试验和XRD定向测试,快速确定其光轴方向的晶体定向新方法.结果表明,CdSe晶体在Ⅱ类相位匹配条件下的有效非线性系数d_(eff)为d_(15)sinθ,倍频转换效率与方位角无关;在Ⅰ类相位匹配条件下其有效非线性系数d_(eff)恒等于0,无倍频输出.根据理论计算结果,运用定向新方法,针对VUVG法生长出的外观无方向特征的CdSe晶体,经定向切割、研磨和抛光,初步加工出基频波长为9.6 μm的CdSe晶体Ⅱ类相位匹配倍频元件, 尺寸达9.5 mm×9.5 mm×18 mm.     

硫化亚铜对电极在量子点敏化太阳电池中的应用

报道了一种基于硫族金属复合物N₄H₉Cu₇S₄前驱体溶液制备硫化亚铜对电极的新方法. 分别制备了TiO₂纳米颗粒多孔薄膜和TiO₂纳米棒阵列结构的光阳极, 并在此基础上研究了基于硫化亚铜对电极的CdS/CdSe量子点敏化太阳电池的光电性能, 同时结合电化学阻抗技术考察了硫化亚铜对电极的催化性能. 结果表明: 与铂电极相比, 本方法制备的硫化亚铜电极对多硫电解质具有更高的催化活性, 所组装的CdS/CdSe量子点敏化太阳电池具有更优的光伏性能.     

Fluorescence Labeling and Determination of Pepsin with CdSe Quantum Dots

Based on the solid phase/liquid deposition CdSe quantum dots (QD) were synthesized using selenium and cadmium‐salt as precursor at room temperature. The average diameter of CdSe QD estimated from the high resolution transmission electron microscopy (HRTEM) graph and absorption spectra was ca. 3–3.5 nm. The mercaptoacetic‐acid stabilized CdSe QD exhibited ultraviolet absorption at 350 and 380 nm and strong fluorescence emission at 481.6 nm, respectively. When conjugated with pepsin, the fluorescence peak intensity of CdSe QD decreased considerably and the fluorescence peak shifted to 467.2 nm. Under optimal conditions, a concentration in 5–50 mg· L^?1 of pepsin could be determined on the basis of fluorescence decrease ratio of CdSe QD, with a detection limit 3δ of 0.36 mg·L^?1 (n=10). The proposed method was applied to detection of the concentration of pepsin in human gastric juice.