CdS量子点敏化ZnO纳米棒阵列电极的制备和光电化学性能

采用连续式离子层吸附与反应法制备了CdS量子点敏化的ZnO纳米棒电极.应用扫描电子显微镜(SEM)、X射线衍射(XRD)和透射电子显微镜(TEM)对CdS量子点/ZnO纳米棒电极的形貌、晶型和颗粒尺寸进行了分析和表征;采用光电流-电位曲线和光电流谱研究了不同CdS循环沉积次数及不同沉积浓度对复合电极的光电性能影响.结果表明,前驱体浓度都为0.1mol·L-1且沉积15次敏化后的ZnO纳米棒阵列电极光电性能最好.与单纯的ZnO纳米棒阵列电极和单纯的CdS量子点电极相比,其光电转换效率显著提高,单色光光子-电流转换效率(IPCE)在380nm处达到76%.这是因为CdS量子点可以拓宽光的吸收到可见光区,并且在所形成的界面上光生载流子更容易分离.荧光光谱实验进一步说明了光电增强的原因是,两者间形成的界面中表面态大大减少,有利于减少光生电子和空穴的复合.     

CdTe/CdS共敏化TiO2电极材料的制备与光电性能

将电沉积法和化学浴沉积法结合,分别将CdTe和CdS量子点纳米晶材料引入到TiO_2纳米管阵列上制备CdTe/CdS量子点共敏化TiO_2光电极。利用扫描电镜、X射线衍射和X射线能量色散光谱等测试手段对所得样品的形貌、晶型和组分进行表征。在模拟太阳光照射条件下,通过电化学工作站测试其光电化学性能。研究结果表明,相对于单一量子点敏化CdS/TiO_2和CdTe/TiO_2光电极而言,共敏化CdTe/CdS/TiO_2光电极表现出更好的光电转化性能,短路电流密度和光电转换效率分别可以达到3.1 m A·cm~(-2)和1.85%。此外,采用电化学阻抗测试技术对材料性能提升的原因进行深入的探究。     

基于原位形成p-n结的新型光电化学传感器检测Hg~(2+)

利用简单方法合成了水溶性的巯基乙酸修饰的硫化镉(CdS)量子点。通过静电吸附,用聚二甲基二烯丙基氯化铵(PDDA)将CdS修饰到氧化铟锡(ITO)电极上。在电子供体三乙醇胺(TEA)的存在下,CdS修饰的ITO电极具有稳定的阳极光电流。Hg2+原位吸附于CdS表面形成的p型半导体HgS与n型半导体CdS形成p-n结,能够促进电子-空穴的分离与电荷传输,使CdS量子点的光电流增大。研究了反应前驱体中Cd,S摩尔比、反应溶液的pH值、回流时间等条件对所合成的量子点与Hg2+相互作用的影响。此外,还研究了电解质溶液的pH值、外加电压、反应时间对Hg2+增大CdS量子点光电流的影响。基于此,构建了灵敏检测Hg2+的光电化学传感器。该传感器对Hg2+响应的线性范围为4.0×10-8~2.0×10-5mol/L,检出限为2.4×10-8mol/L,回收率为98.3%~103.5%。     

基于DNA电化学发光传感器研究金纳米颗粒对量子点的电化学发光影响

纳米金颗粒具有高的消光系数和良好的表面等离子体共振特性, 其等离子体共振特性受纳米金颗粒的尺寸和周围环境等因素的影响. 本文基于半导体纳米晶电化学发光信号对金纳米颗粒的距离依赖性制备了DNA电化学发光传感器. 首先利用循环伏安法(CV)在玻碳电极(GCE)表面原位沉积金纳米颗粒(AuNPs), 巯基丙酸包裹的CdS量子点(QDs)与氨基修饰的双链DNA (dsDNA)通过酰胺键缩合, 形成量子点修饰的双链DNA(QDs-dsDNA). 最后将QDs-dsDNA 通过dsDNA 另一端的巯基组装到纳米金表面, 得到CdS QDs-DNA/AuNPs/GCE电化学发光传感器. 在优化电极表面QDs-dsDNA密度、金纳米颗粒沉积方法等实验条件的基础上, 对不同传感器的表面性质进行了表征, 如形貌和电化学阻抗等. 进一步通过控制纳米金和CdS QDs之间的DNA研究了纳米金对CdS QDs发光信号的影响作用. 结果显示DNA链的长度和类型对发光信号有着重要的影响. 最后将此传感器用于环境污染物的DNA损伤检测, 显示出很好的灵敏响应.     

0D/1D碳点修饰硫化镉纳米线异质结增强可见光光催化性能（英文）

硫化镉(CdS)作为一种对可见光响应的窄带隙半导体(带隙宽度约为2.4 eV),具有合适的能带位置,近年来受到越来越多的重视.然而在光催化过程中,光生电子与空穴的快速复合极大地限制了CdS的实际应用,如何提高光生电子-空穴对的分离效率成为研究重点.一维CdS纳米棒(1D CdS NWs)具有较大的长径比,能快速有效地转移光生载流子.零维碳点(0D C-dots)是一种粒径在10 nm以下的新型纳米碳材料,其作为助催化剂能够加快光生载流子传递速率,可提高材料光催化性能.因此,通过C-dots对CdS NWs进行修饰并形成异质结,利用C-dots助催化剂的作用以提升CdS NWs的光催化性能,具有一定的可行性.本文成功构建了一种0D/1D碳点修饰CdS NWs异质结(C-dots/CdS NWs),并考察其光催化性能.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和紫外-可见(UV-Vis)吸收光谱等技术对系列C-dots/CdS NWs样品进行表征.研究发现,C-dots成功负载在CdS NWs的表面并形成异质结.通过测试系列样品在可见光照射下光催化降解罗丹明B(RhB)以及光催化产氢性能发现,C-dots的修饰能够有效增强CdS NWs的光催化性能,其中0.4%C-dots/CdS NWs表现出最佳的光催化降解RhB活性,其经可见光照射60 min即可实现对RhB的完全降解(相同条件下CdS NWs需要180 min).同时自由基捕获实验表明,·O_2~–是降解罗丹明B过程中的主要活性基团.在光催化产氢性能测试中,0.4%C-dots/CdS NWs样品表现出最高的光催化产氢能力,产氢速率可达1633.9μmol g~(-1) h~(-1),比纯CdS的(196.9μmol g~(-1) h~(-1))提高了8.3倍,并且C-dots/CdS NWs具有良好的稳定性.研究发现,在可见光照射下,C-dots/CdS NWs能够产生较强的光生电流,且形成的0D/1D C-dots/CdS NWs异质结具有良好的电子传输能力,实现了C-dots/CdS NWs光生电子与空穴的有效分离,从而增强了光催化性能.     

CdS/石墨烯纳米复合物的可见光催化效率和抗光腐蚀行为

制备了一系列CdS纳米晶/石墨烯(CdS/GR)复合物,并在可见光照条件下评价了其光催化降解亚甲基蓝的光催化效率和抗光腐蚀行为. 研究表明,石墨烯的引入加速了CdS纳米晶(NCs)光生电子的迁移速率,抑制了其光生电子-空穴的复合,有效改善了其光催化降解有机污染物的性能. CdS/GR复合物中的石墨烯含量显著影响其光催化效率,其中石墨烯含量为4.6%的光催化剂效率最高,其光电流是CdS NCs的2.3倍. 利用光电化学和X射线衍射技术进一步证实,石墨烯的引入抑制了CdS NCs光腐蚀的发生,提高了CdS/GR复合物的光催化稳定性.     

聚3-甲基噻吩修饰量子点硫化铅连接TiO2纳米结构膜的光电化学研究

采用原位化学法在纳米结构TiO2电极上制备了量子点PbS(Q-PbS), 并用电化学方法在TiO2/Q-PbS表面聚合3-甲基噻吩[poly(3-Methylthiophene), PMeT]. 研究结果表明, PMeT和Q-PbS单独修饰纳米结构TiO2电极和PMeT修饰Q-PbS连接纳米结构TiO2电极的光电流产生的起始波长都向长波方向移动; 在可见光区光电转换效率均比纳米结构TiO2的光电转换效率提高显著; PMeT与Q-PbS修饰的纳米结构TiO2之间存在p-n异质结. 在一定条件下p-n异质结的存在有利于光生电子/空穴的分离, 提高了光电转换效率.     

单晶二氧化钛纳米棒阵列的修饰及其在量子点敏化太阳电池中的应用(英文)

使用TiCl4溶液对单晶TiO2纳米棒阵列(TNRs)进行修饰,通过在TiO2纳米棒表面合成TiO2纳米颗粒来提高TNRs的表面积,提高TNRs对量子点的吸附能力,并在此基础上研究了TiCl4修饰时间对基于单晶TNRs的CdS/CdSe量子点敏化太阳电池光伏性能的影响,同时结合强度调制光电流谱(IMPS)研究了TiO2纳米棒阵列的电子传输性能.结果表明:TiCl4修饰可以大幅提高基于单晶TNRs的CdS/CdSe量子点敏化太阳电池的光伏性能,在TiCl4修饰时间为60 h时,其短路电流密度和光电转换效率分别由修饰前的(2.93±0.07)mA·cm-2和0.36%±0.02%提高至(8.19±0.12)mA·cm-2和1.17%±0.07%.同时,IMPS测试表明电子在单晶TiO2纳米棒阵列中的传输速率高于在TiO2纳米颗粒薄膜中的传输速率,证明了单晶TiO2纳米棒阵列在电子传输方面的优越性.     

高效的CdS/Ti-Fe2O3异质结光阳极:研究Z型电荷迁移机制增强光电化学水氧化活性

近年来以Z型机制为转移的光催化体系成微光电化学分解水领域的研究热点.相比较传统的异质结,Z型异质结能够保留具有高氧化能力与高还原能力的位点,从而提高光电化学效率.其中,证明电荷的Z型迁移机制成为研究人员努力的方向,比较有效的证明方法包括自由基捕获、XPS分析和检测还原位点等.对于Z型异质结,界面电场处电荷的迁移行为是至关重要的,但目前常用的证明手段对界面电场处电荷的迁移行为研究还比较少.因此,本文精心设计了CdS/Ti-Fe₂O₃异质结光阳极来探索光电化学分解水中的电荷转移行为.采用开尔文探针测试、表面光电压谱测试和瞬态光电压谱测试等光物理测试手段监测CdS/Ti-Fe₂O₃Z型异质结光阳极界面电场中光生电荷的迁移行为.其中,开尔文探针和表面光电压测量表明,CdS/Ti-Fe₂O₃界面驱动力有利于激发电子快速迁移至CdS;由于Z型异质结是一个双光子的过程,因此在瞬态光电压的过程中采取了双光束策略,即用不同波长的光分别从两个半导体侧进行照光,以充分发挥内层CdS的电子传输层的作用.结果表明,在双光束照射下界面电场增强,使得更多Ti-Fe₂O₃电子与CdS空穴结合,使得更多Ti-Fe₂O₃电子与CdS空穴结合,更多的空穴迁移到Ti-Fe₂O₃的表面去参与反应,充分证明了CdS/Ti-Fe₂O₃光阳极的Z型迁移机制.基于界面电场有效的电荷迁移与分离的分析,对Z型异质结光阳极进行了光电化学的测试,与单纯Ti-Fe₂O₃光阳极相比,CdS/Ti-Fe₂O₃光阳极表现出优异的光电化学性能.其中,25CdS/Ti-Fe₂O₃光阳极的光电流密度在1.23V(相对于标准氢电极)达到1.94 mA/cm²,比单纯Ti-Fe₂O₃光电流高出两倍.阻抗测试结果表明,CdS/Ti-Fe₂O₃光阳极能够减小电荷传输阻力,从而加快电荷分离效率,这也间接证明了Z型光阳极的成功构筑,因此,本文提供了一个有效且新颖的手段来证明光电化学分解水中光催化系统的Z型电荷转移机制.     

温度对聚酰胺-胺树形分子模板法制备CdS量子点的影响

为了研究温度对聚酰胺-胺(PAMAM)树形分子的模板法制备硫化镉(CdS)量子点的影响, 以4.5代(G4.5, 64个甲酯端基)PAMAM树形分子为模板, 在－10～30 ℃的温度范围内制备了分散良好的CdS量子点. 用透射电子显微镜(TEM)表征了CdS量子点的形貌、尺寸; 用紫外-可见光谱(UV-Vis)和光致发光光谱(PL)表征了CdS量子点的光学性能. 发现在相同条件下, 制备温度从－10 ℃升高到30 ℃, CdS量子点粒径从1.8 nm增大到3.4 nm, 其中在10 ℃时制备的量子点的尺寸分布最窄; CdS量子点的吸收和发射光谱均随温度增大而红移, 其中10 ℃时制备的量子点的室温光致发光效率最高. 这表明制备温度决定了树形分子的配位基团与Cd^2＋的分离速度, 并影响了CdS量子点的成核和生长过程, 从而最终决定了CdS量子点的尺寸及尺寸分布、光致发光颜色和发光效率.     

CdTe/CdS量子点的Ⅰ-Ⅱ型结构转变与荧光性质

制备了壳层厚度可以精确控制的CdTe/CdS核壳量子点, 利用紫外-可见吸收光谱、光致发光光谱、透射电镜和时间分辨光谱等技术, 分析了CdS壳层厚度对CdTe量子点的荧光量子产率和光谱结构的影响规律. 发现了不同于CdSe/CdS, CdSe/ZnS, CdTe/ZnS等核壳量子点的荧光峰展宽、大幅度红移以及荧光寿命大幅度增加现象. 根据能带的位置关系, 随着CdS厚度的增加, CdTe从Ⅰ型结构逐渐过渡到Ⅱ型核壳结构. 对于Ⅱ型CdTe/CdS核壳量子点, 不仅存在CdTe核区导带电子与价带空穴间的直接复合, 还存在CdS壳层导带电子与CdTe核价带空穴界面处的间接复合, 发光机制的变化导致荧光峰的展宽、明显红移和荧光寿命的增加. 当壳层过厚时, 壳层表面新引入的缺陷会阻碍荧光寿命和量子产率的进一步提高.     

Fine tuning of the morphology of copper oxide nanostructures and their application in ambient degradation of methylene blue

A low-cost, green, and reproducibly non-injection one-pot synthesis of high-quality CdS quantum dots (QDs) is reported. The synthesis was performed in the open air by mixing precursors cadmium stearate and S powder into a new solvent N-oleoylmorpholine. An overlapped nucleation-growth stage followed by a dominated growth stage was observed. The resulting QDs exhibited well-resolved absorption fine substructure and a dominant band-edge emission with a narrow size distribution (the full width at half maximum (fwhm) was only 22-24nm). The maximum photoluminescence (PL) quantum yield (QY) was as high as 46.5%. Highly monodispersed CdS QDs with tunable sizes and similar PL fwhm and QYs could also be obtained from the CdS QDs in a large-scale synthesis. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs with high crystallinity had a cubic structure. A significant PL improvement and a continuous QY increase for the CdS QDs were observed during a long storage time in air and in a glovebox under room temperature. A slow surface reconstruction was proposed to be the cause for the PL enhancement of CdS QDs.     

叶酸受体靶向CdS量子点应用于HepG2细胞成像研究

0引言量子点(quantum dots,QDs)又称半导体纳米晶体(semiconductor nanocrystal),是一种由Ⅱ-Ⅵ族或Ⅲ-Ⅴ族元素组成的尺寸在2￣20nm之间,稳定的微     

基于GSH-CdTe/CdS量子点的荧光变化研究hsDNA与盐酸洛美沙星-Cu(Ⅱ)配合物的相互作用

采用水相法合成了谷胱甘肽(GSH)修饰的CdTe/CdS量子点(GSH-CdTe/CdS QDs). 透射电子显微镜表征结果表明, GSH-CdTe/CdS QDs的粒径分布均匀, 分散性好. 在Tris-HCl(pH=7.6)缓冲液中, 由于静电引力作用, 带正电的盐酸洛美沙星(LMFH)-Cu(Ⅱ)配合物[LMFH-Cu(Ⅱ)]吸附到带负电的GSH-CdTe/CdS QDs表面形成基态复合物, 导致GSH-CdTe/CdS QDs的荧光猝灭. 随后, 向GSH-CdTe/CdS QDs-LMFH-Cu(Ⅱ)配合物体系中加入鲱鱼精DNA(hsDNA), hsDNA可诱导LMFH-Cu(Ⅱ)配合物从GSH-CdTe/CdS QDs表面脱落而嵌入到hsDNA的双螺旋结构中, 使GSH-CdTe/CdS QDs的荧光恢复. 通过对GSH-CdTe/CdS QDs荧光的可逆调控, 利用荧光光谱、 紫外-可见吸收光谱和共振瑞利散射光谱研究了hsDNA与LMFH-Cu(Ⅱ)配合物的相互作用. 通过对比GSH-CdTe/CdS QDs与LMFH相互作用的光谱性质, 讨论了GSH-CdTe/CdS QDs-LMFH-Cu(Ⅱ)-hsDNA的相互作用机理, 模拟了作用过程, 从而建立了一种研究氟诺喹酮类药物的金属配合物与核酸相互作用机制的光谱方法.     

Fabrication of Hemoglobin/Ionic Liquid Modified Carbon Paste Electrode Based on the Electrodeposition of Gold Nanoparticles/CdS Quantum Dots and Its Electrochemical Application

A novel H₂O₂ amperometric biosensor based on the electrodeposition of gold nanoparticles (AuNPs) and CdS quantum dots (CdS QDs) onto a carbon paste electrode (CPE) and immobilizing hemoglobin (Hb) with ionic liquid (IL), is presented in this article. The modification process of the electrode was monitored by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Due to synergistic effects of AuNPs, CdS QDs and IL, the biosensor exhibited high stability and good bioelectrocatalytic ability to H₂O₂ with a linear concentration range from 10 to 750 µM and a detection limit of 4.35 µM (S/N=3).     

Facile fabrication of fluorescent-superhydrophobic bifunctional ligand-free quantum dots

We present herein a facile strategy for fabrication of fluorescent-ultrahydrophobic bifunctional ligand-free CdS quantum dots (QDs) using cadmium acetate, sodium sulfide as starting materials, and ethanol as the solvent. The as-prepared CdS QDs without ligands exhibit good photochemical stability and photoluminescence (PL) in comparison with the previously reported aqueous CdS QDs. The effects of various experimental variables, including Cd/S molar ratio, reaction time, and reaction temperature on the optical properties of the obtained CdS QDs have been systematically investigated. Subsquently, dodecanethiol was introduced to modify these CdS QDs, further conferring them with superhydrophobic property, along with good compatibility with polymers. The features and structures of the as-prepared QDs and their hybrids on UV–Vis, PL spectroscopy, Fourier transform infrared, transmission electron microscope, X-ray diffraction, and contact angle have been disscussed.     

Dual-functional photocatalysis boosted by electrostatic assembly of porphyrinic metal-organic framework heterojunction composites with CdS quantum dots

Photocatalytic dual-functional reaction under visible light irradiation represents a sustainable development strategy. In detail, H₂ production coupled with benzylamine oxidation can remarkably lower the cost by replacing sacrificial agents. In this work, Cd S quantum dots(Cd S QDs) were successfully loaded onto the surface of a porphyrinic metal-organic framework(Pd-PCN-222) by the electrostatic selfassembly at room temperature. The consequent Pd-PCN-222/CdS heterojunction composites...     

Ru/CdS Quantum Dots Templated on Clay Nanotubes as Visible-Light-Active Photocatalysts: Optimization of S/Cd Ratio and Ru Content

A nanoarchitectural approach based on in situ formation of quantum dots (QDs) within/outside clay nanotubes was developed. Efficient and stable photocatalysts active under visible light were achieved with ruthenium-doped cadmium sulfide QDs templated on the surface of azine-modified halloysite nanotubes. The catalytic activity was tested in the hydrogen evolution reaction in aqueous electrolyte solutions under visible light. Ru doping enhanced the photocatalytic activity of CdS QDs thanks to better light absorption and electron–hole pair separation due to formation of a metal/semiconductor heterojunction. The S/Cd ratio was the major factor for the formation of stable nanoparticles on the surface of the azine-modified clay. A quantum yield of 9.3 % was reached by using Ru/CdS/halloysite containing 5.2 wt % of Cd doped with 0.1 wt % of Ru and an S/Cd ratio of unity. In vivo and in vitro studies on the CdS/halloysite hybrid demonstrated the absence of toxic effects in eukaryotic cells and nematodes in short-term tests, and thus they are promising photosensitive materials for multiple applications.     

Copolymer nanosphere encapsulated CdS quantum dots prepared by RAFT copolymerization: synthesis,characterization and mechanism of formation

Cadmium sulfide (CdS) quantum dots (QDs) encapsulated in block copolymer spheres were synthesized by an aqueous emulsion polymerization process. First, stable dispersions of CdS QDs in water were prepared using a polymer dispersant, either poly(acrylic acid) or a random copolymer having an average of ten acrylic acid and five butyl acrylate units. These polymer dispersants were prepared by reversible addition-fragmentation chain transfer polymerization. Then, the CdS QDs dispersed in water were encapsulated in a polystyrene shell using an emulsion polymerization process. Spectroscopic and microscopic techniques were used to characterize the resulting nanocomposites. Optical properties of QDs in polymer microspheres were investigated by UV-vis and fluorescence spectroscopic studies. Particle sizes of all CdS QD samples were calculated from absorption edges using Henglein's empirical curve. Transmission electron microscopy was used to determine the size and morphology of CdS QD samples. These observations were used to elucidate the mechanism of formation of the resulting well-defined polymer-encapsulated CdS nanoparticles.