a硫磺共聚物基质内的免费配体硫化镉纳米粒子的合成
Summary
Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.
Abstract
Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired.
Introduction
虽然证明对合成是有用的，常规的脂族配位体存在许多用于纳米颗粒的光子和电化学装置的实施挑战。脂肪族配体高度绝缘，疏水性，并构成显著障碍电化学表面反应。1因此，一些研究已经开发了配体交换和配体剥离与功能部分或剥去配体取代这些脂肪族配体的协议，露出了光秃秃的纳米粒子表面1 – 3这些反应，但是，提出几个问题的内在。它们显著添加到合成过程的复杂性，不总是进行完全，并能恶化的纳米颗粒，使用这些技术时，器件制造过程中，可反过来强加显著问题的表面上。4
我们已经开发了硫共聚物，其可以用作硫化镉纳米粒子的合成过程中既高温溶剂和硫源。5该共聚物是基于由。Chung等人 ，使用元素硫和1,3-二异丙烯基苯（DIB）开发的网络共聚物。6在我们的情况下，甲基单体实现的，而不是DIB。的甲基单体限制交联反应，否则将产生一个高的分子量网络共聚物。5,6-只有一个乙烯基官能团的对甲基苯乙烯单体的存在促进形成低聚自由基一旦加热，这使得硫共聚物具体操作为并联纳米颗粒合成过程中的液体溶剂和硫源5，硫聚合物通过元素硫加热至150℃，这将导致在S 8环转变到线性结构液体硫双基形式产生。接下来，甲基注入我 n要在甲基分子与硫原子1:50摩尔比液体硫。5所述的甲基双键与硫链反应产生的共聚物，如在图1中。5硫共聚物，然后冷却和镉前体加入。然后将该混合物再加热到200℃，在此期间，硫共聚物熔化，并在纳米颗粒成核和生长过程发起的溶液内5 A 20：是用来硫镉前体的摩尔比为1:1，所以，只有某些硫在反应过程中消耗掉。5该共聚物由一旦反应已终止的固体聚合物基质中悬浮它们稳定纳米颗粒。5的共聚物可以在合成之后被去除，导致生产不具有的CdS纳米粒子的有机配位配体，如在图2 5所示
内容】“>在这项工作中提出的合成方法是比较简单的，在文献中提出的其它方法的比较。1 – 3,7在传统连接的纳米颗粒已被证明存在问题，或不希望的，适用于不同范围的应用这种技术可以打开大门更高吞吐量测试，其中一个批次纳米粒子可用于检查后续functionalizations的完整频谱，而不需要复杂且耗时的配位体剥离或交换过程。2,4,8,9这些未连接的纳米颗粒也提供机会通过消除碳源，以减少印刷纳米器件通常观察到的碳缺陷的数量。10 – 16本详细的协议旨在帮助他人实施这种新方法，并帮助推动各种会发现场的积极使用它具有特殊的意义。Protocol
Representative Results
Discussion
We have developed a method to synthesize CdS nanoparticles within a sulfur copolymer matrix. This sulfur copolymer is composed of elemental sulfur and methylstyrene.5 An important feature of this method is that the copolymer can be used as both a high-temperature solvent and a sulfur source that reacts with a cadmium precursor to produce CdS nanoparticles in solution.5 The critical step in the procedure is the synthesis of the sulfur copolymer with a suitable ratio of methylstyrene and sulfur. The u…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors would like to acknowledge the State of Washington for supporting this research through the University of Washington Clean Energy Institute Exploratory Fellowship Program, and National Science Foundation (NSF) Sustainable Energy Pathway (SEP) Award CHE-1230615.
Materials
| Sulfur (S8), 99.5% | Sigma Aldrich | 84683 | |
| α-methylstyrene, 99% | Sigma Aldrich | M80903 | |
| Cadmium acetylacetonate (Cd(acac)), 99.9% | Sigma Aldrich | 517585 | Highly Toxic |
| Chloroform (CHCl3), 99.5% | Sigma Aldrich | C2432 | |
| Hotplate / magnetic stirrer | IKA RCT | 3810001 | |
| Temperature controller with probe and heating mantle | Oakton Temp 9000 | WD-89800 | |
| Centrifuge | Beckman Coulter Allegra X-22 | 392186 | |
| Centrifuge Tubes | Thermo Scientific | 3114 | Teflon for resistance to chlorinated solvents |
| TEM with attached EDS detector | FEI Tecnai G2 F-20 with EDAX detector | ||
| TEM Sample Grid | Ted Pella | 1824 | Ultrathin carbon film substrate with holey carbon support films on a 400 mesh copper grid |
| XRD | Bruker F-8 Focus Diffractometer | ||
| Molybdenum coated soda lime glass substrates | 750 nm thick sputtered molybdenum layer | ||
| Quartz Fluorescence Cuvettes | Sigma Aldrich | Z803073 | 10 mm by 10 mm, 4 polished sides with screw top |
| UV-Vis-NIR | Perkin Elmer Lambda 1050 Spectrometer | With 3D WB Detector Module | |
| PL | Horiba FL3-21tau Fluorescence Spectrophotometer |
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