CdS aerogels: Effect of concentration and primary particle size on surface area and opto-electronic properties

Porous aerogels of CdS that exhibit quantum confined optical properties have been prepared by supercritical drying of wet CdS gels prepared by oxidative stripping of nanoparticle capping groups. The water-to-surfactant ratio (W) employed in the preparation of the nanoparticles is found to have a large impact on the surface areas of resultant aerogels, with W=5 samples producing mesoporous samples with the highest surface areas and cumulative pore volumes. In contrast, the concentration of the CdS sol employed in the gelation has only a small effect on the porosity characteristics, but a large impact on the apparent crystallite and chromophore sizes in as-prepared aerogels. Higher concentrations of the sol result in larger crystallite sizes and lower degrees of quantum confinement, as evidenced by a red shift in the absorbance spectra.     

原位合成具有高可见光催化活性的C3N4/CdS纳米复合材料

以硫氰酸铵和氯化镉为原料,采用无模板混合高温煅烧法一步合成氮化碳/硫化镉纳米晶(C3N4/CdS)的复合半导体材料。采用X射线衍射、傅立叶变换红外光谱和透射电镜等技术对其结构和形貌进行了表征。以有机污染物罗丹明B (RhB)为模拟污染物对复合催化剂的可见光催化活性进行测试。结果表明, C3N4/CdS复合材料中CdS以六方相纳米晶的形式均匀分散; CdS的复合基本不改变C3N4主体结构及聚合度;与纯C3N4相比,复合材料在可见区的光吸收能力有所增强。合适的能带匹配有利于光生载流子的迁移,抑制了其复合速率。在可见光照射下,复合半导体能够更加快速的降解有机污染物,且保持很好的稳定性。     

原位合成具有高可见光催化活性的C3N4/CdS纳米复合材料

以硫氰酸铵和氯化镉为原料,采用无模板混合高温煅烧法一步合成氮化碳/硫化镉纳米晶(C3N4/CdS)的复合半导体材料。采用X射线衍射、傅立叶变换红外光谱和透射电镜等技术对其结构和形貌进行了表征。以有机污染物罗丹明B (RhB)为模拟污染物对复合催化剂的可见光催化活性进行测试。结果表明, C3N4/CdS复合材料中CdS以六方相纳米晶的形式均匀分散; CdS的复合基本不改变C3N4主体结构及聚合度;与纯C3N4相比,复合材料在可见区的光吸收能力有所增强。合适的能带匹配有利于光生载流子的迁移,抑制了其复合速率。在可见光照射下,复合半导体能够更加快速的降解有机污染物,且保持很好的稳定性。     

Preparation and photocatalytic properties of silica-supported fine CdS powders

Summary Silica-supported cadmium sulfide, highly active in hydrogen photogeneration from water-methanol-KOH solution, was prepared by sulfidation of Cd²⁺-impregnated SiO₂. The samples consisted of colloidal-size hexagonal crystallites of CdS on amorphous SiO₂. A blue shift of a light absorption edge was observed for the samples with lower CdS content.

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Herstellung und photokatalytische Aktivität von feinen CdS-Pulvern auf SiO₂

Zusammenfassung Es wurde Cadmiumsulfid auf Kieselgel durch Sulfidierung von Cd²⁺-imprägniertem SiO₂ hergestellt, das eine außerordentliche Aktivität bei der Wasserstoff-Photogenerierung aus Wasser-Methanol-KOH-Lösungen zeigte. Der Katalysator bestand aus hexagonalen CdS-Kristalliten von kolloidalen Ausmaßen auf amorphem SiO₂. An Proben mit geringerem CdS-Gehalt wurde eine Blauverschiebung der Lichtabsorption an der Absorptionskante beobachtet.

     

以含铬类水滑石型层状化合物为模板制备硫化物半导体纳米晶

采用类水滑石型混合金属氢氧化物(CdCr-LDH和ZnCdCr-LDH)为前驱体, 通过气-固反应方法, 制备了根植于层状氢氧化物层板中的硫化镉纳米晶和硫化镉/硫化锌复合纳米晶, 通过改变前驱体(CdCr-LDH)中镉和铬的摩尔比可以调控硫化镉纳米晶的粒径.     

纳米硫化镉的合成及其电化学催化性能测试

采用CS2-SDS-正辛醇-水微乳体系制备了硫化镉纳米棒。利用XRD、SEM、TEM对产物进行表征，测试了其对多硫化物电极还原反应的催化性能，并与常规方法合成的大粒度CdS晶体进行对比．结果表明，纳米棒为六方型CdS晶体，直径约12nm．常规法合成的CdS为立方型晶体，平均粒度约为1μm．CdS纳米棒电极对硫化钠／多硫化钠电极反应的电催化活性明显高于大粒度CdS晶体电极．     

聚乙烯醇辅助合成CdS纳米线及其表征

以聚乙烯醇为辅助剂, 使用溶剂热法成功制备CdS纳米线, 并用XRD、TEM、HRTEM、UV-Vis和PL(荧光)发射谱等方法对样品进行表征. 结果表明, 该法制备的CdS纳米线为六方纤锌矿结构, 直径为70 nm, 长约10 μm, 沿[001]晶向择优生长, 具有量子禁域效应. 同时, 根据对比实验结果提出了CdS纳米线的聚合物辅助生长机理.     

黄色硫化镉纳米粒子的共振瑞利散射光谱研究

在高分子聚乙烯醇存在下 ,Cd2 + 与S2 - 反应生成黄色CdS纳米微粒。当CdS浓度小于 5× 1 0 - 4 mol L时 ,它在 4 70nm产生一个最强RRS峰 ,这是由低浓度较小粒径黄色CdS纳米微粒或黄色CdS分子与光源相互作用的结果 ;当CdS浓度大于 7.5× 1 0 - 4 mol L时 ,在 5 2 0nm产生一个最强的特征RRS峰。黄色CdS纳米微粒体系在可见光区无吸收峰。当CdS纳米微粒的浓度在 7.5× 1 0 - 4 ～ 2 .0× 1 0 - 3mol L范围内 ,所得纳米粒子的粒径为 4 3nm。实验表明 :光源发射强度分布和CdS纳米粒子的形成是产生其RRS光谱峰的主要原因     

巯萘剂表面修饰的CdS纳米微粒的合成及发光特性

用疏萘剂(TN)作为表面修饰剂,在甲醇溶液中合成了CdS/TN纳米微粒,用TEM测得纳米微粒呈球形,其粒径约10nm,吸收光谱和荧光光谱研究表明,[S^2-]/[TN]浓度比、TN和镉离子的浓度对CdS/TN纳米微粒的粒径及发光特性具有显著影响,且随着条件的改变,CdS/TN纳米微粒的发射波长红移100nm,表现出明显的量子尺寸特性.XPS显示所制得表面修饰纳米微粒的核为CdS.     

活体生物膜控制合成纳米半导体硫化镉

目前 ,用于合成和制备纳米材料的方法除化学和物理方法[1～ 4] 外 ,还有仿生法[5～ 7] ,但尚未见到利用活体生物膜来合成无机纳米材料的报道 .本文利用绿豆芽通过生物膜控制合成了纳米ＣｄＳ .1　实验部分将市售新鲜绿豆芽用去离子水洗净后放入盛有 0 .1ｍｏｌ·Ｌ- 1 Ｎａ2 Ｓ水溶液的试管中 ,浸没茎部 ,露出叶片 .2 4ｈ后取出 ,用去离子水冲洗掉豆芽外部的Ｎａ2 Ｓ溶液 ,转放到盛有ＣｄＣｌ2 水溶液的试管中 ,用同法浸泡 2 4ｈ .取出豆芽 ,小心用玻璃棒将豆芽茎外的黄色ＣｄＳ转入无水乙醇中 .取少量ＣｄＳ乙醇溶液 ,经超声振荡后上铜网 ,…     

Surfactant-ligand co-assisted solvothermal technique for the synthesis of different-shaped CdS nanorod-based materials

1-D nanorods, twinrods, golfclubs, and tripods of CdS were prepared via a surfactant-ligand co-assisted solvothermal method at 160°C. The surfactant of S-dodecylisothiounium bromide (C₁₂) used in the process was favorable for synthesis of different-shaped CdS nanorod with high aspect ratio. X-ray diffraction (XRD) and TEM images showed that the 1-D nanorods had wurtzite phase and others had a zinc blende core and wurtzite arms. The morphologies of CdS prepared under different conditions suggested the “template-assistance” of the surfactant and that the nonaqueous organic media are important for the self-assembling of inorganic components at atomic level.     

CdS纳米棒的制备、表征及其形成机理

以三辛基膦(TOP)为单一配位溶剂,二水合乙酸镉和硫粉为前驱体,用高温热解的方法制备CdS纳米棒.通过X射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)、紫外-可见(UV-Vis)分光光度计、荧光(PL)光谱、傅里叶变换红外(FTIR)光谱和核磁共振磷谱(31PNMR)等方法对样品的结构、形貌和光学特性进行了表征.考察了前驱体Cd/S摩尔比和反应物浓度对硫化镉纳米结构的影响.实验结果表明,该法制备的CdS纳米棒为纤锌矿结构,直径为4.0nm,长度为28.0nm,沿[001]方向择优生长,具有量子限域效应.同时,对CdS纳米晶的形成机理进行了初步的探讨.     

Enhancement on the structural,functional, optical and morphological properties of temperature treated silver sulfide nanostructures

The Silver Sulfide (Ag₂S) nanostructures were synthesized via the facile co-precipitation method. Thorough study and analysis were carried out to reveal and compare the structural, optical, functional, and morphological characteristics of as-synthesized samples annealed at various temperatures. The XRD analysis characterized the structural properties of Ag₂S nanoparticles, which unveiled the excellent crystallinity and monoclinic structure. The as-synthesized samples show an average crystallite size of 52 nm–41.7 nm. The modes of vibration and peak position of metal sulfides in Ag₂S nanoparticles were investigated through the FTIR technique. The optical attributes of prepared samples were scrutinized using UV–Vis analysis, which portrays the cut-off wavelength in the range of 1192–1223 nm for non-annealed and annealed Ag₂S nanoparticles, alongside the optical band gap is about 0.86 eV–0.96 eV. This work elucidates a novel approach to synthesis and scrutinises the characteristics of Ag₂S nanoparticles by subjecting them to distinct annealing temperatures precisely, as-prepared, 200 °C and 400 °C.     

非离子型微乳状液制备均分散硫化镉

近年来,半导体胶体CdS溶胶或悬浮液已引起人们极大兴趣,其原因在于它的光电性质,特别是它的光化学性质及光催化性质。而上述性质均与CdS胶体粒子的大小和形状密切相关,所以作为光能转换及光催化反应的硫化镉溶胶不仅纯度要求高,而且对粒子的尺寸、形状及均匀性的要求也银严格。目前,主要用水解法、苯硫酚法及用阴离子型表面     

Optical Properties of CdS Nanobelts and Nanosaws Synthesized by Thermal Evaporation Method

By a simple one-step H2-assisted thermal evaporation method, high quality CdS nanos-tructures have been successfully fabricated on Au coated Si substrates in large scale. The as-synthesized CdS nanostructures consisted of sword-like nanobelts and toothed nanosaws with a single-crystal hexagonal wurtzite structure. The deposition temperature played an important role in determining the size and morphology of the CdS nanostructures. A combi-nation of vapor-liquid-solid and vapor-solid growth mechanisms were proposed to interpret the formation of CdS nanostructures. Photoluminescence measurement indicated that the nanobelts and nanosaws have a prominent green emission at about 512 nm, which is the band-to-band emission of CdS. The waveguide characteristics of both types of CdS nanos-tructures were observed and discussed.     

基于表面富Cd2+的硫化镉量子点荧光增强测定半胱氨酸

采用一步法可控合成了表面富Cd2+的水溶性荧光硫化镉量子点,并成功用于半胱氨酸测定.通过控制镉-硫前驱体合适比例,使合成的量子点表面富含Cd2+,它们能与半胱氨酸分子中巯基结合引起体系量子点荧光增强,由此实现半胱氨酸的选择性定量分析检测.在pH=2.87的B-R缓冲体系中,测定半胱氨酸的线性区间分别为0.01～5.0 μmol/L和5.0～100 μmol/L;检出限(3σ)为3.3 nmol/L,且其它氨基酸干扰小,可应用于混合氨基酸合成样品、复方氨基酸注射液和人血清实际样品中半胱氨酸的检测.     

功能性硫化镉纳米荧光探针荧光猝灭法测定核酸

报道了无机纳米溶胶CdS的合成，并对其进行了功能化修饰。研究了功能性CdS纳米溶胶的荧光性质。对小牛胸腺DNA进行了定量测定，考察了各种影响因素，在最佳实验条件下，该方法的线性区间0.1-1.5mg/L，检测限为0.018mg/L。与传统的有机染料相比，该方法简单、快速、灵敏度高。     

BiOCl nanostructures with different morphologies: Tunable synthesis and visible-light-driven photocatalytic properties

BiOCl nanostructures including microspheres,microflowers,microplates,and nanoplates,have been synthesized by a simple solvothermal method using bismuth nitrate and sodium chloride as raw materials without adding any additives.Structure and morphology of the products were characterized by powder X-ray diffraction,scanning electron microscopy,and transmission electron microscopy.The results indicated that the as-prepared microspheres and microflowers were composed of nanosheets.Although with different shape and lateral size,the nanoplates and microplales were all single-crystalline plates with exposed {001) facets.It was found that the volume ratio of polyethylene glycol 400 and H₂O in the solvent played a key role in the morphology of the products,and the possible growth mechanism was also discussed.The photocatalytic measurements indicated that the BiOCl samples exhibit good photocatalytic properties towards Rhodamine B.     

Fabrication of CdS films with superhydrophobicity by the microwave assisted chemical bath deposition

A simple method of microwave assisted chemical bath deposition (MA-CBD) was adopted to fabricate cadmium sulfide (CdS) thin films. The superhydrophobic surface with a water contact angle (CA) of 151 degrees was obtained. Via a scanning electron microscopy (SEM) observation, the film was proved having a porous micro/nano-binary structure which can change the property of the surface and highly enhance the hydrophobicity of the film. A possible mechanism was suggested to describe the growth of the porous structure, in which the microwave heating takes an important role in the formation of two distinct characteristic dimensions of CdS precipitates, the growth of CdS sheets in micro-scale and sphere particles in nano-scale. The superhydrophobic films may provide novel platforms for photovoltaic, sensor, microfluidic and other device applications.     

Chemical deposition of semiconducting cadmium selenide quantum dots in thin film form and investigation of their optical and electrical properties

Cadmium selenide quantum dots with cubic crystal structure are chemically deposited in thin film form using selenosulfate as a precursor for selenide ions and ammonia buffer with double role: as a ligand and as a pH value controller. The optical band gap energies of as-deposited and thermally treated cadmium selenide thin films, calculated within the framework of parabolic approximation for the dispersion relation, on the basis of equations which arise from the Fermi's golden rule for electronic transitions from valence to conduction band, are 2.08 and 1.77 eV, correspondingly. The blue shift of band gap energy of 0.34 eV for as-deposited thin films with respect to the bulk value is due to the quantum size effects (i.e., nanocrystals behave as quantum dots) and this finding is in agreement with the theoretical predictions. During the thermal treatment the nanocrystals are sintered, the increase of crystal size being in correlation with the decrease of band gap energy. The annealed thin films are practically non-quantized. From the resistance-temperature measurements, on the basis of the dependence of ln(R/Ω) vs 1/T in the region of intrinsic conduction, the thermal band gap energy (at 0 K) of 1.85 eV was calculated.