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.

Dikkat: Kadmiyum öncüleri son derece zehirlidir ve büyük bir dikkatle ele alınması gerekir. Uygun koruyucu kıyafet giyiniz uygun mühendislik kontrollerini kullanın ve danışmak ilgili malzemeler güvenlik veri sayfaları (MSDS). Buna ek olarak, nanopartiküller oluşumu ilave tehlikeleri olabilir. Burada tarif edilen reaksiyonların eylemsiz bir atmosfer içinde deneyleri yürütmek üzere, standart bir vakum gaz manifoldu ile yürütülmektedir. Tüm kimyasallar ticari olarak alındı ​​ve alındığı şekilde kullanıldı. Bu protokol, kısa bir süre önce başka bir yerde tarif edilen daha önce geliştirilmiş sentezleme yöntemi, dayanmaktadır. 5 1. Kükürt Kopolimer Sentezi <ol><li> Erimiş element kükürt hazırlanması <ol><li> Talep element kükürt bağlı bir kondansatör ve ısı sondası ile 50 ml&#39;lik bir üç boyunlu bir şişe içinde (4 g, 124.8 mmol, S 8,% 99.5). Vakum ve azot birkaç kez pompa ve boşaltma çevrimi gerçekleştirin. </li><li> nitrojen altında ısıKükürt san renkli sıvı hale gelmesine neden olur karıştırılarak 150 ° C,. </li></ol></li><li> Kükürt Kopolimerin Hazırlanması <ol><li> Bir kez kükürt, tüm sıvı içine çözününceye, hemen çözüm α-metilstiren (330 ul, 2.5 mmol,% 99) enjekte edilir. </li><li> 10 dakika boyunca 500 rpm&#39;de karıştırılarak 185 ° C&#39;ye kadar ısı çözeltisi. kopolimer formları gibi, çözüm nihayet koyu kırmızı bir renk üreten, turuncu, sarı rengi değişecektir. </li><li> ısı çözelti alınır ve oda sıcaklığına soğumaya bırakın. soğur, kopolimer yavaş yavaş lastik katı bir portakal oluşturmak için kristalize olur. Bu aşamada, kopolimer, bir sonraki sentez için oda sıcaklığında saklanabilir ya da hemen kullanılabilir. </li></ol></li></ol> 2. CdS Nanoparçacık Sentezi <ol><li> , Önceki adımda elde edilen üç boyunlu bir şişeye kadmiyum asetilasetonat (Cd (AcAc), 900 mg, 2.9 mmol,% 99.9) ilave böyleceToz eşit bir katı kükürt kopolimer (4.0 g, 116 mmol) üstüne yerleştirilir. </li><li> azot ve vakum birkaç kez balona pompa ve tasfiye çevrimi gerçekleştirin. </li><li> azot altında karıştırılarak 200 ° C&#39;ye kadar çözelti ısıtılır. kükürt kopolimer eritmek ve kadmiyum öncüsü ile karıştırın ve nanoparçacık çekirdeklenme ve büyüme süreçleri başlayacak olacaktır. </li><li> nanopartiküller 30 dakika boyunca büyümeye olanak sağlar. Not:.. Nanopartiküller büyümesini etkileyecektir reaksiyon süresi değiştirilerek, bu nedenle ayarlamak için nanopartiküllerin son boyutu mümkündür 5 30 dakika reaksiyon süresi 7-10 nm arası bir boyuta aralığı 5 </li><li> ısı çözelti alınır ve oda sıcaklığına soğumaya bırakın. </li><li> Soğuduktan sonra, oda sıcaklığında, şişe ve mağaza katı nanokompozit çıkarın. </li></ol> 3. Kükürt Kopolimeri çıkarın ve Nanoparçacıklar izole <ol><li> Kükürt Kopolimer çıkarılması </strong&gt; <ol><li> 20 ml&#39;lik bir cam şişe içinde nanokompozitinin (200 mg), koyun ve kloroform (20 mi) ilave edin. </li><li> nanokompositlerin kırmak ve çözüm içinde nanopartiküller askıya, 1 saat için bir ultrasonikatör ve sonikasyon flakon yerleştirin. </li><li> İki adet 30 ml&#39;lik santrifüj tüplerine aynlır ve her bir kloroform diğer 20 ilave edin. </li><li> 15 dakika boyunca 8736 xg solüsyonu (göreceli merkezkaç kuvveti) santrifüj. </li><li> yerleşmiş nanopartiküller rahatsız değil emin olun, santrifüj tüplerine gelen kükürt kopolimer süzün. </li></ol></li><li> Nanopartiküller izolasyonu <ol><li> 15 dakika boyunca her santrifüj tüpünün (30 mi) ve sonikasyon kloroformun eklenmesi yerleşmiş nano-tanecikleri yeniden dağıtılır. </li><li> kükürt kopolimer tüm kaldırıldı sağlamak için bölümler 3.1.4, 3.1.5 ve 3.2.1 üç kez daha açıklanan adımları tekrarlayın. Bir kez kükürt kopolimerin tüm kaldırılır boşaltıldı Çözelti No lo olacaknger turuncu bir renge sahiptir. </li><li> Her bir santrifüj tüpüne kloroform (2 mi) eklenerek nihai nano partikülleri toplamak. </li><li> Bir 20 ml&#39;lik bir cam şişeye (4 ml çözelti toplam) toplanan nano parçacıkları birleştirilir ve kloroform kaldırmak için vakum altında cam şişe yerleştirin ve nano-parçacıkları kuru. Bu aşamada elde edilen nanopartiküllerin kitle belirlenebilir ve başlatıcı madde ile ürünün mol oranları kullanılarak reaksiyonun verimi tespit etmek için öncüler başlangıç ​​kütlesine göre. </li></ol></li></ol> CdS Nanoparçacıkları karakterize 4. <ol><li> Transmisyon Elektron Mikroskobu <ol><li> 1 saat boyunca izole edilmiş kloroform içinde nano-tanecikleri (20 mg), (20 mi) ve ultrasonicate seyreltilir. </li><li> 15 dakika için bu kloroform içinde çözelti (5/5 ml damla) ve sonikasyon ile seyreltilir. </li><li> 400 üzerinde holey karbon destek filmleriyle bir ultra ince karbon filmi alt tabaka üzerine nihai çözüm BırakBakır Transmisyon Elektron Mikroskobu (TEM) ızgara örgü. </li><li> bir cam şişede TEM ızgara yerleştirin ve örnek herhangi bir kalan solventin çıkması için, bir gece boyunca vakum altında tutun. </li><li> Kurutma işlemi tamamlandıktan sonra, 200 kV hızlandırma gerilimi, 3 spot boyutu ve ekli Enerji Dağılımı X-ışını spektroskopisi (EDS) detektörü kullanılarak TEM görüntüleri kazanır. </li></ol></li><li> X-ışını difraksiyon <ol><li> kloroform içinde izole edilmiş nano parçacıkları (10 mg / ml) ile seyreltilir. </li><li> 10 dakika boyunca her biri, deterjan, iyonu giderilmiş su, aseton ve izopropil alkol içinde sonike temizleyin molibden kaplanmış soda camı alt-tabakalar (1 cm2). Son olarak, döküm damla önce 10 dakika için bir hava plazma temizleyici yüzeyin temizlenmesi. </li><li> Bırak 7 ul artışlarla 4.2.2 den substratlar üzerine 4.2.1 den çözüm attı. </li><li> filmler kuruduktan sonra, X-ışını difraksiyonu (XRD) veri elde. bir tarama hızında 7,000 veri noktalarını kullanarak veri toplamakbir Cu-Ka X-ışını kaynağı ve 1,54059 Â bir dalga boyu ile saniyede 1 veri noktası. </li></ol></li><li> çözüm Spektroskopisi <ol><li> kapalı bir kuartz küvet içinde 30 dakika ve yeri örnekleri için kloroform ve sonikasyon izole nano-tanecikleri (0.1 mg / ml) dağıtılır. </li><li> malzeme süspansiyonunun kolaylaştıran 70 ° C&#39;ye kadar bölüm 2.6 nanokompozit ve formamid bölüm 1.2.3&#39;de sülfür kopolimeri (1 mg / ml), 700 rpm&#39;de karıştırılmıştır ve ısıyı dağıtmak. </li><li> Her üç numune için fotolüminesans (PL) ve absorbans spektrumlarını kazanır. ultraviyole, görünür ve kızıl ötesine yakın aralık (UV-Vis NIR) boyunca uzanan bir üç dedektörü ile bir spektrometre kullanılarak optik absorbans ölçümleri yürütün. 330 nm&#39;lik bir eksitasyon dalga boyunda bir flüoresan spektrofotometre kullanılarak PL ölçümlerini. NOT: bölümlerde tartışılan teknikleri kullanarak nanopartikülleri tanımlamak için özel bir protokol 4.1.5, 4.2.4, birnd 4.3.2 yaygın olarak kullanılan özel ekipman doğasına bağlı olarak değişir, bu yüzden biz burada sadece genel karakterizasyon parametreleri sunuyoruz. İlgilenen okuyucu CdS nanopartiküller bu analiz teknikleri kullanılarak ilgili daha fazla bilgi için birçok yorum kağıtları yöneliktir 17 -. 19 </li></ol></li></ol>

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The authors disclose no competing financial interests.

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 use of methylstyrene and in the appropriate concentration is important to form the copolymer that can be stored as a powder at room temperature, and then be heated to produce a liquid to allow the nanoparticle synthesis to occur. During the synthesis, only some of the sulfur reacts with the cadmium precursor, while the remainder stays within the sulfur copolymer.5 Once the reaction solution is cooled and solidified, this procedure produces CdS nanoparticles suspended within a sulfur copolymer matrix.5 The copolymer can subsequently be removed, producing nanoparticles that do not have conventional organic ligands.5 A limitation of our method however, is that once the copolymer is removed, the nanoparticles are prone to aggregation, which can be prevented when conventional organic ligands are present. This makes it difficult to control the self-assembly of our nanoparticles during film formation. The nanoparticle size can be tuned by varying the reaction time, although another limitation is that this method produces nanoparticles with a higher level of polydispersity in size than conventional techniques,5,18 which broadens the absorption and emission spectra of our nanoparticles.
This nascent synthesis method can be useful in a range of fields where the presence of conventional aliphatic ligands diminishes the charge transfer or surface reaction properties of the nanoparticles. Furthermore, this synthesis method is relatively simple in comparison to other methods that require multistep ligand exchange or ligand stripping procedures to remove conventional aliphatic ligands.1-4 For example, one set of nanoparticles could be functionalized with a range of ligands to produce nanoparticles with a spectrum of different properties.9 In addition, this method could be used to produce nanoparticle based devices where the presence of organic ligands would otherwise introduce unwanted carbon impurities.10,12

sentezi için yararlı olduğu kanıtlanmıştır rağmen, geleneksel alifatik ligandlar fotonik ve elektrokimyasal cihazlarda nanopartiküllerin uygulanması için bir takım zorluklar mevcut. Alifatik ligandlar son derece hidrofobik yalıtım ve elektrokimyasal yüzey reaksiyonları önemli bir engel teşkil etmektedir. 1 Buna göre, çeşitli çalışmalar geliştirdik ligand değişimi ve ligand çıplak nanoparçacık ortaya çıkarmak için fonksiyonel parçalarının veya kaldırdığını ligandlarla Bu alifatik ligandları yerini protokolleri sıyırma vardır yüzey 1 -. 3 Bu reaksiyonlar, ancak birkaç içsel sorunlar oluşturmaktadır. Onlar önemli ölçüde zaman tamamlanması gitmeyin, sentetik sürecin karmaşıklığı ekleyin ve bu teknikleri kullanırken sırayla cihaz üretim sırasında önemli sorunlar empoze edebilirsiniz nanopartiküller, yüzeyini kötüleşmesine neden olabilir. 4 Bir kükürt kopolimeri geliştirdikCdS nanopartiküllerin sentezi sırasında yüksek sıcaklık, çözücüye ve kükürt kaynağı hem de kullanılabilir. 5 bu kopolimer Chung ve diğ. element kükürt ve 1,3-benzeni (DIB) kullanan tarafından geliştirilen bir ağ kopolimerine dayanmaktadır. 6&#39;da bizim davamız, bir metilstiren monomer yerine DIB uygulanmaktadır. Aksi takdirde, yüksek moleküler ağırlıklı ağ kopolimeri üretecek çapraz bağlama reaksiyonları metilstiren monomer sınırlar. 5,6 metilstiren monomer sadece bir vinilik fonksiyonel grubun varlığı kükürt kopolimer sağlar ısıtılmış ve oligomerik radikallerin oluşumunu teşvik nanoparçacık sentezi sırasında paralel olarak sıvı çözücü ve kükürt kaynağı olarak faaliyet göstermektedir. 5 Spesifik olarak, kükürt, polimer doğrusal yapılı sıvı sülfür diradikal forma geçiş S 8 halka olur, 150 ° C, kükürt elementi ısıtılması ile elde edilir. Daha sonra, metilstiren i enjekte edilir<html> 5 metilstiren çift bağ, Şekil 1 &#39;de gösterildiği gibi, kopolimer üretmek üzere kükürt zincirleri ile reaksiyona giren kükürt atomu metilstiren moleküllerinin 1:50 mol oranında sıvı sülfür nBu.. 5 kükürt kopolimeri daha sonra soğutuldu ve kadmiyum ön-madde olan eklendi. Bu karışım daha sonra çözelti içinde, 200 ° C&#39;ye ısıtılmış bu süre boyunca, kükürt kopolimeri erir ve nanoparçacık çekirdeklenme ve büyüme prosesleri başlatılmış olan 5 A 20:. Kadmiyum ön kükürt 1 mol oranı kullanıldığında, sadece bazı şekilde kükürt reaksiyon sırasında tüketilir. 5 bu kopolimer, reaksiyon sona erdiğinde, katı bir polimer matrisi içinde süspansiyon haline getirilerek nano partikülleri stabilize eder. 5 kopolimer sentezden sonra çıkarılabilir olmayan CdS nanopartiküllerin üretimi ile sonuçlanan Şekil 2&#39;de tasvir edildiği gibi, organik koordine ligandlar. 5 ontent &quot;&gt; Bu çalışmada sunulan sentetik yöntem literatürde diğer yöntemlerle karşılaştırıldığında nispeten basit 1 -.. 3,7 geleneksel bağlandı nanopartiküller sorunlu ya da istenmeyen kanıtlanmıştır nerede uygulamaların çeşitli bir yelpazede için geçerli olan bu teknik can nanopartiküllerin bir serisi, karmaşık ve zaman işlemleri soyma veya değişim ligand alıcı gerek kalmadan takip eden functionalizations tam bir spektrumunun incelemek için kullanılabilir daha yüksek verim test açık kapı. 2,4,8,9 Bu bağlanmamış nanopartiküller imkanı da sunmaktadır karbon kaynağı ortadan kaldırarak yaygın basılı nanoparçacık cihazlarda görülen karbon kusurları sayısını azaltmak için - 10. 16 Bu ayrıntılı bir protokol diğerleri bu yeni yöntemi uygulamak yardımcı olmak ve bulacaksınız alanlarda çeşitli aktif kullanımını teşvik yardımcı olmak için tasarlanmıştır özel önem bu.

<table><tbody><tr><td>Sulfur (S&lt;sub&gt;8&lt;/sub&gt;), 99.5%</td><td>Sigma Aldrich</td><td>84683</td><td></td></tr><tr><td>&amp;alpha;-methylstyrene, 99%</td><td>Sigma Aldrich</td><td>M80903</td><td></td></tr><tr><td>Cadmium acetylacetonate (Cd(acac)), 99.9%</td><td>Sigma Aldrich</td><td>517585</td><td>Highly Toxic</td></tr><tr><td>Chloroform (CHCl&lt;sub&gt;3&lt;/sub&gt;), 99.5%</td><td>Sigma Aldrich</td><td>C2432</td><td></td></tr><tr><td>Hotplate / magnetic stirrer</td><td>IKA RCT&amp;nbsp;</td><td>3810001</td><td></td></tr><tr><td>Temperature controller with probe and heating mantle</td><td>Oakton Temp 9000</td><td>WD-89800</td><td></td></tr><tr><td>Centrifuge</td><td>Beckman Coulter Allegra X-22</td><td>392186</td><td></td></tr><tr><td>Centrifuge Tubes</td><td>Thermo Scientific</td><td>3114</td><td>Teflon for resistance to chlorinated solvents</td></tr><tr><td>TEM with attached EDS detector</td><td>FEI Tecnai G2 F-20 with EDAX detector</td><td></td><td></td></tr><tr><td>TEM Sample Grid</td><td>Ted Pella</td><td>1824</td><td>Ultrathin carbon film substrate with holey carbon support films on a 400 mesh copper grid</td></tr><tr><td>XRD</td><td>Bruker F-8 Focus Diffractometer</td><td></td><td></td></tr><tr><td>Molybdenum coated soda lime glass substrates</td><td></td><td></td><td>750 nm thick sputtered molybdenum layer</td></tr><tr><td>Quartz Fluorescence Cuvettes</td><td>Sigma Aldrich</td><td>Z803073</td><td>10 mm by 10 mm, 4 polished sides with screw top</td></tr><tr><td>UV-Vis-NIR</td><td>Perkin Elmer Lambda 1050 Spectrometer</td><td></td><td>With 3D WB Detector Module</td></tr><tr><td>PL</td><td>Horiba FL3-21tau Fluorescence Spectrophotometer</td><td></td><td></td></tr></tbody></table>

synthesis of ligand-free cds nanoparticles within a sulfur copolymer matrix

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.

Şekil 3a TEM görüntüsü kükürt kopolimeri tamamen kaldırılmıştır önce kükürt kopolimer içinde çekirdekli olan küçük CdS nanopartiküller (3-4 nm) gösterir. Şekil 3a&#39;da görüntü çözeltisi 200 ° C&#39;ye ulaştığında hemen sonra nanopartikül çözeltisinin bir bölümü alınarak elde edildi. Şekil 3b, kükürt kopolimeri tamamen olmuştur önce 30 dakika süre ile çözelti içinde büyüdü büyük nano-tanecikleri (7-10 nm) göstermektedir kaldırıldı. Şekil 3c Şekil 3b vurgulanan alanın daha yüksek bir büyütme görüntü gösterir. Şekil 3c Bir nanoparçacık 3.3 Å olarak ölçüldü özellikle açık atom düzlemi aralığına sahiptir. 3.3 Â atom düzlem aralık çinko blend CdS veya wurtzite CdS (002) düzlemi boşluk (111) düzlemi aralığı ile tutarlıdır. Bir kere kükürt kopolimeri tamamen kaldırılır 3d gösterileri Şekilve kloroform içinde eritildi, nanopartiküller bir araya toplar. Şekil 3d sunulan EDS veri CdS stokiyometrisini doğruladı (yaklaşık 1: 1) ve kükürt kopolimer etkin bir şekilde kaldırıldı onaylar. Bir önceki yayında, biz kükürt kopolimer tümüyle kaldırılır kez bu nanopartiküller geleneksel organik bağlar yok olduğunu göstermek için kızılötesi spektroskopi (FTIR) ve proton nükleer manyetik rezonans spektroskopisi (1H NMR) dönüşümü Fourier kullandı. 5 Tek çalışma Nag tarafından ve. ark., metal sülfit nanopartiküller etkili anyonik sülfür türlerinin ile lige edilebilir olduğunu göstermiştir. 7 Biz nanopartiküller bu yöntem Benzer nanopartikül yüzey üzerinde sülfür türlerinin yapılandırdığımız kullanılarak yapılan varsaymak. Şekil 3d sunulan EDS veriler nanopar sülfür türlerinin varlığında uygun olarak kükürt bir hafif bir stoikiometrik fazlalıkta göstermektedirTICLE yüzey. Damla dökme nanoparçacık ince film için XRD modeli Şekil 4&#39;te sunulan ve wurtzite oluşumu ile uyumludur ve muhtemelen blend yapısal CdS çinkodur. 26.6 derece bulunan tepe çinko-blende CdS veya wurtzite CdS (002) düzlemi boşluk (111) düzlemi aralığı ile uyumludur ve TEM görülen düzlemsel aralığı doğruluyor 3.3 Å bir atom düzlemi aralığı, karşılık Şekil 3c görüntüsü. Şekil 5&#39;te gösterildiği gibi kükürt kopolimeri ve nano bileşiği, her dispersiyon konsantrasyonu eşittir olduğundan veriler, nano bileşiği, sadece, kükürt kopolimer ile karşılaştırıldığında önemli ölçüde geliştirilmiş emicilik arzetmektedir göstermektedir. UV-Vis spektroskopisi kullanılarak analiz edildi. Şekil 6 gösterisinde sunulan fotolüminesans veri nanokompozit toplu mavi-kaymıştır bir zirveye sergilerCdS bandaralıklı (510 nm, 2.4 eV), kükürt kopolimer zirve nispeten küçük olduğu görülmektedir. İzole nanopartiküller da vardı kükürt kopolimer çıkarıldı kez UV-Vis-NIR ve PL spektroskopi kullanılarak incelendi. 7 gösterileri hem UV-Vis-NIR ve PL veri Şekil. Şekil 6&#39;da, nanopartiküller CdS dökme bandaralıklı ve 450-550 nm aralığında olan küçük emme kenarı ile buna uygun geniş bir absorpsiyon spektrumu merkezlenmiş geniş bir PL noktası vardır. Kükürt polimerin çıkarıldığında, nanopartikül yüzey artık pasifize ve sarkan bağların varlığı nedeniyle yüzey kusurları içerir. Bu, daha sonra, nanokompozit materyal için, Şekil 5 ve 6&#39;da sunulan spektrumları karşılaştırıldığında PL ve absorbans spektrumlarını genişletmek ve kırmızı kayması yeni yüzey aracılı enerji seviyeleriyle varlığı neden 18,20 -. Ek olarak 22Ayrıca spektrumları genişletir ki, kuantum hapsi etkiler gösteren nanopartiküllerin bir popülasyonda nanopartiküller sonuçlarının polidispersitelerinin. 23 Bu nedenle, bizim daha önceki çalışmaları ile birlikte, bu veriler iddia bu nanopartiküller geleneksel kusur kez organik ligandlar pasifleştirme yok destekler kükürt kopolimer kaldırılır. 5. Ayrıca, bu veri kükürt kopolimer kaldırılmasına önce CdS nanopartiküllerin yüzey kusurları pasifleştirdiği olduğunu göstermektedir. <img alt="Şekil 1" src="/files/ftp_upload/54047/54047fig1.jpg" /> Kükürt kopolimer Şekil 1. sentezi ve yapısı. Elemental kükürt kükürt kopolimer üretmek için metilstiren ile reaksiyona giren bir doğrusal yapılı sıvı kükürt diradikali üretmek için ısıtılır. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig1large.jpg" target="_blank">Büyük halini görmek için tıklayınız</a>bu rakamın. <img alt="şekil 2" src="/files/ftp_upload/54047/54047fig2.jpg" /> Şekil 2. Nanoparçacık büyüme ve İzolasyon. CdS nanopartiküller çekirdekli ve kükürt kopolimer içinde büyür. Reaksiyon tamamlandıktan sonra, kükürt kopolimer ligand-serbest CdS nanopartiküller üretmek için çıkarılır. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig2large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> <img alt="Şekil 3," src="/files/ftp_upload/54047/54047fig3.jpg" /> İzole CdS nanopartiküllerin Şekil 3. TEM görüntüleri. A) kopolimer içinde büyümeye başlayan 3-4 nm CdS nanopartiküller. B) reaksiyon sonlandırılır kez nanopartiküller nm 7-10. S kopolimer bu aşamada. C) vurgulanan Büyütülmüş görüntü hala mevcut, b. d bölge) S kopolimerin çıkarılmasından sonra TEM görüntüsü. Ankastre EDS verileri gösterir. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig3large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> <img alt="Şekil 4," src="/files/ftp_upload/54047/54047fig4.jpg" /> Şekil CdS nanoparçacık filmler 4. XRD paterni. XRD paterni wurtzite veya çinko blend CdS oluşumu ile uyumludur. Substrata. Nedeniyle molibden doruğudur <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig4large.jpg" target="_blank">bu rakamın daha büyük bir versiyonunu görmek için lütfen buraya tıklayınız.</a> <img alt="Şekil 5," src="/files/ftp_upload/54047/54047fig5.jpg" /> Kükürt kopolimer ve nanokompozitinin Şekil 5, absorbans spektrokopisi. Nano bileşiği anlaml sergileyenicantly sadece kükürt kopolimere göre absorpsiyon tepe geliştirilmiş. Dağılım içinde. Her iki malzemeler eşit konsantrasyonları <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig5large.jpg" target="_blank">bu rakamın daha büyük bir versiyonunu görmek için lütfen buraya tıklayınız.</a> <img alt="Şekil 6," src="/files/ftp_upload/54047/54047fig6.jpg" /> Kükürt kopolimer sergiler nispeten küçük fotolüminesans. Iken kükürt kopolimer ve nanokompozit için Şekil 6. Fotolüminesans spektroskopisi. Nanokompozit, mavi-kaymıştır CdS toplu bandaralıklı (510 nm, 2.4 eV) dan bir tepe sergileyen <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig6large.jpg" target="_blank">bir görüntülemek için tıklayınız Bu rakamın daha büyük bir versiyonu.</a> <img alt="Şekil 7," src="/files/ftp_upload/54047/54047fig7.jpg" /> FiguLigand ücretsiz CD nanopartiküllerin 7. absorbans ve Fotolüminesans spektroskopisi yeniden. PL veriler 510 nm&#39;de odaklanmış olan geniş bir zirve göstermektedir. UV-Vis-NIR verileri 450-550 nm aralığında zayıf emme omuz ile geniş bir emme eğrisini göstermektedir. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54047/54047fig7large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a>

Watch this Scientific Journal Video about Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix at JoVE.com

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

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.

Bir Kükürt Kopolimer Matrix içinde ligand-serbest CdS Nanopartiküller Sentezi

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature ...

synthesis-ligand-free-cds-nanoparticles-within-sulfur-copolymer

Nanyang Technological University

Research

JoVE Journal

Chemistry

9.4K Görüntüleme.  University of Washington. 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.

Video: Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

Tek molekül Görüntüleme için kompakt Kuantum Noktaları

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

Mühendislik

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Şarj-Ayırma Nanokristaller ve Bunların Katılar Yoluyla Güneş Enerjisi Hasat

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

Kimya

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Sentezi, Karakterizasyonu ve Hibrid Au / CdS ve Au / ZnS Çekirdek / Shell Nanopartiküller işlevselleştirilmesi

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, quantum dots should be highly fluorescent and small/monodisperse in size. While commonly used cadmium-based quantum dots possess these qualities, they are potentially toxic due to the possible release of Cd2+ ions through nanoparticle degradation. Indium-based quantum dots, specifically InP/ZnS, have recently been explored as a viable alternative to cadmium-based quantum dots due to their relatively similar fluorescence characteristics and size. The synthesis presented here uses standard hot-injection techniques for effective nanoparticle growth; however, nanoparticle properties such as size, emission wavelength, and emission intensity can drastically change due to small changes in the reaction conditions. Therefore, reaction conditions such temperature, reaction duration, and precursor concentration should be maintained precisely to yield reproducible products. Because quantum dots are not inherently soluble in aqueous solutions, they must also undergo surface modification to impart solubility in water. In this protocol, an amphiphilic polymer is used to interact with both hydrophobic ligands on the quantum dot surface and bulk solvent water molecules. Here, a detailed protocol is provided for the synthesis of highly fluorescent InP/ZnS quantum dots that are suitable for use in biomedical applications.

In this protocol, the synthesis of Cd-free InP/ZnS quantum dots (QDs) is detailed. InP-based QDs are gaining popularity due to the toxicity of Cd2+ ions that may be released through nanoparticle degradation. After synthesis, QDs are solubilized in water using an amphiphilic polymer for use in biomedical applications.

Biyomedikal Uygulamalar için uygundur InP / ZnS Kuantum Noktaları Cd-serbest sentezi

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

Doğrudan Floresan Görüntüleme kullanma Nanoparçacık-polimer kompozitler Gelişmiş Bileşim Analizi

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

Facet-to-facet Linking of Shape-anisotropic Colloidal Cadmium Chalcogenide Nanostructures

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energy-dispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.

A protocol detailing how shape-anisotropic colloidal cadmium chalcogenide nanocrystals can be covalently linked via their end facets is presented here.

Model model şekil-Yönbağımlı kolloidal kadmiyum Chalcogenide taşınımı bağlama

Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be ...

Synthesis of a Thiol Building Block for the Crystallization of a Semiconducting Gyroidal Metal-sulfur Framework

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and porous metal-dithiolene network in the highly ordered single crystalline state. Unlike the highly reactive free-standing thiols, which tend to decompose and complicate the crystallization of metal-thiolate open frameworks, the thioester reacts in situ to provide the thiol species, serving to mitigate the reaction between the mercaptan units and the metal centers, and to improve crystallization consequently. Specifically, the thioester was synthesized in a one-pot procedure: an aromatic bromide (hexabromotriphenylene) reacted with excess sodium thiomethoxide under vigorous conditions to first form the thioether intermediate product. The thioether was then demethylated by the excess thiomethoxide to provide the thiolate anion that was acylated to form the thioester product. The thioester was conveniently purified by standard column chromatography, and then used directly in the framework synthesis, wherein NaOH and ethylenediamine serve to revert in situ the thioester to the thiol linker for assembling the single-crystalline Pb(II)-dithiolene network. Compared with other methods for thiol synthesis (e.g., by cleaving alkyl thioether using sodium metal and liquid ammonia), the thioester synthesis here uses simple conditions and economical reagents. Moreover, the thioester product is stable and can be conveniently handled and stored. More importantly, in contrast to the generic difficulty in accessing crystalline metal-thiolate open frameworks, we demonstrate that using the thioester for in situ formation of the thiol linker greatly improves the crystallinity of the solid-state product. We intend to encourage broader research efforts on the technologically important metal-sulfur frameworks by disclosing the synthetic protocol for the thioester as well as the crystalline framework solid.

Here, we present a one-pot, transition-metal-free synthesis of thiols and thioesters from aromatic halides and sodium thiomethoxide, followed by the preparation of single crystals of a metal-dithiolene network using thiol species generated in situ from the more stable and tractable thioester.

Bir yarıiletken Gyroidal Metal-kükürt çerçeve kristalleşme için Thiol yapı taşı sentezi

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and ...

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.

The main goal of this work is to elucidate the role of capping agents in regulating the size of palladium nanoparticles by combining in situ small angle x-ray scattering (SAXS) and ligand-based kinetic modeling.

Çekirdekleşme ligand-aracılı ve Paladyum Metal nano tanecikleri gelişmesi

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution ...

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bis(thiourea) Cadmium Chloride Crystals and the Subsequent CdS Obtention

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of 367 nm using the chemical bath deposition technique are studied comparatively. Two experiments are performed to make a comparison: one without UV light and the other with the aid of UV light. Both experiments are performed under equal conditions, at a temperature of 343 K and with a pH of 3.2. The precursors used are cadmium chloride (CdCl2) and thiourea [CS(NH2)2], which are dissolved in 50 mL of deionized water with an acidic pH. In this experiment, the interaction of electromagnetic radiation is sought at the moment the chemical reaction is carried out. The results demonstrate the existence of an interaction between the crystals and the UV light; the UV light assistance causes crystal growths in an acicular shape. Also, the final product obtained is cadmium sulfide and shows no evident difference when synthesized with or without the use of UV light.

The Effect of Ultraviolet Radiation on the Chemical Bath Deposition of Bisthiourea Cadmium Chloride Crystals and the Subsequent CdS Obtention

This article presents a protocol for the synthesis of bis(thiourea) cadmium chloride crystals by chemical bath deposition. Two experiments are described: one aided by ultraviolet light compared to one without ultraviolet light.

Kimyasal banyosu biriktirme ultraviyole radyasyon Bis(thiourea) kadmiyum klorür kristaller ve sonraki CD Obtention etkisi

In this work, the effects on the preparation of bis(thiourea) cadmium chloride crystals when illuminated with ultraviolet (UV) light at a wavelength of ...