Name: photochemical oxidative growth of iridium oxide nanoparticles on cdse@cds nanorods
Uploaded: 2016-02-11T15:00:00.000+00:00
Duration: 5 min 41 s
Description: Watch this Scientific Journal Video about Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods at JoVE.com

这项研究是由计划和预算委员会和以色列科学基金会（批准号:十一分之一百五十二）的I-CORE项目的支持。我们感谢化学的Schulich商学院与Technion工业 - 以色列理工学院的实验室装修和启动包。我们也感谢皇家化学学会的许可，从http://dx.doi.org/10.1039/C4TA06164K适应材料在这个手稿中使用。 Kalisman博士感谢他们的支持Schulich商博士后研究。我们感谢亚龙考夫曼博士为他的HR-TEM和HAADF以及Kamira Weinfeld博士协助她与XPS表征援助。

1.量子点21的合成<ol><li> TOP的制备:Se前体<ol><li>在用隔膜小瓶结合58毫克硒粉末与0.360克三正辛基膦（TOP）中。 </li><li>超声振荡顶部:硒混合物，直到它是一个没有明确的固体。 </li></ol></li><li>硒化镉的合成<ol><li>结合3.0克三辛基氧化膦（TOPO），280毫克正 - 十八烷基酸（ODPA），和60毫克的CdO在装有热电偶25毫升三颈圆底烧瓶3毫米×8 mm的圆柱形搅拌棒（插入定制玻璃适配器），回流冷凝器用T型接头（中心颈），和橡胶隔膜。组装所有玻璃 - 玻璃接头高温真空润滑脂。 T型接头连接到一个端部的Schlenk线，可以清洁的惰性气体和真空之间进行切换，在连接的另一端，以鼓泡。 注意:氧化镉是非常有毒的，应称重并加入到圆底烧瓶中的封闭的env内ironment诸如手套箱。 </li><li>放置圆底烧瓶装置以加热套，并与惰性气体吹扫。 </li><li>加热该固体在圆底烧瓶至150℃，并确保以开始剧烈搅拌一次化合物熔化（约60-80℃）。为了避免超过目标温度，加热至100℃，然后150℃，一旦加热速度减慢或稳定。 </li><li>脱气在真空下将该混合物（在150℃）为至少1小时，同时仍然搅拌。确保T型接头是不对外开放的起泡或油会被吸进瓶中，舒伦克线。当从气体移动到真空小心地慢慢过渡，以避免超过沸腾了。 </li><li>重新填充有惰性气体的烧瓶（并继续流动气体在样品），并升高温度到350℃。该溶液应该打开清楚它加热，并在烧瓶壁过量固体可以通过在烧瓶小心旋流收集。 </LI&gt; <li>注入1.5克顶部进入通过隔膜烧瓶中。使溶液温度，然后再继续稳定。 注:尽量减少空气/湿气通过保持在惰性气氛下的隔膜小瓶的顶部，并尽可能快地注入其注入量。 </li><li>注入所有的TOP:硒混合物（在第1.1节中制备）进入通过隔膜的烧瓶中，使用宽针注入TOP:硒作为快速且均匀越好。 </li><li>来进行反应所需的时间，并从加热套除去。 <ol><li>对于非常小的种子刚刚注射前，离火。对于较大的种子取出注射TOP后，立即从热烧瓶:硒或等待长达3分钟后。再等导致更大的种子。 </li></ol></li><li>使反应冷却到约100℃，并注入大约5毫升脱气的甲苯中。转移溶液至小瓶惰性气氛下进行清洁。 没有德:为了简化此过程10ml甲苯可以放置在20ml的小瓶在惰性气体的恒定流动的隔片。使用大约一半的甲苯，注入到冷却的混合物，然后将冷却的混合物转移回该小瓶中。 </li><li>种子清洗<ol><li>放入50毫升的离心管中的溶液。 </li><li>加甲醇（约5毫升）以沉淀出从甲苯混合物的种子。 </li><li>离心3,400 XG 5分钟。 </li><li>滗澄清的上清液并再溶解在甲苯中沉淀（5-10）溶液中。 </li><li>重复步骤总通过1.2.10.2在1.2.10.4至少三次。 </li></ol></li><li>稀释在甲苯中的种子中的一小等分试样以测量350-800纳米之间紫外可见（UV-VIS）吸收。使用峰来确定，如在文献22中描述的硒化镉种子的浓度和大小。 </li></ol></li></ol> 2.去籽罗的合成DS 21 <ol><li> TOP的制备:•前兆<ol><li>用搅拌棒的小瓶结合1.2克的S用15g的顶部。 </li><li>搅拌至清无物（通常至少24小时）。 </li><li>测量0.62克该混合物与隔膜的小瓶。 </li></ol></li><li> TOP的制备:硒化镉前体<ol><li>测量从步骤1的CdSe种子的适当体积（基于紫外可见峰）与隔膜的小瓶。 注意:对于5×10计算浓度-5 2.25纳米的种子（从UV-Vis光谱22算出这两个值），使用300微升的溶液。 </li><li>使用真空线，直到种子干燥蒸发甲苯。真空下不要离开超过5-10分钟一次干，因为这会降低种子的质量。 </li><li>重新溶解所有的干种子的于0.5g TOP的。 </li></ol></li><li>硒化镉@ CDS的合成<ol><li>结合60毫克丙基酸（PPA），3.35克TOPO，1.080克O​​DPA和230毫克的CdO在装有热电偶（插在定制玻璃适配器）25毫升三颈圆底烧瓶3毫米×8 mm的圆柱形搅拌棒，回流冷凝器用T型接头（中心颈），以及橡胶隔膜。组装所有玻璃 - 玻璃接头高温真空润滑脂。 T型接头连接到一个端部的Schlenk线，可以清洁的惰性气体和真空之间进行切换，在连接的另一端，以鼓泡。 注意:氧化镉是非常有毒的，应称重并加入到圆底封闭的环境里，例如一个手套箱。 PPA在一些国家调节，并且可以通过丁基膦酸（BPA，72毫克），或己基膦酸（HPA，80毫克）代替，虽然双酚A和HP​​A通常导致较短的杆。 </li><li>放置圆底烧瓶装置以加热套，并与惰性气体吹扫。 </li><li>加热在圆底烧瓶中，以120℃的固体，并确保以开始剧烈搅拌一旦化合物 -DS熔体（约60-80℃）。为了避免超过目标温度，加热至90℃，然后120℃，一旦加热速度减慢或稳定。 </li><li>脱气在真空下将该混合物（在120℃）为至少半小时，同时仍然搅拌。 <ol><li>确保T型接头是不对外开放的起泡或油会被吸进瓶中，舒伦克线。当从气体移动到真空小心地慢慢过渡，以避免超过沸腾了。使用冷阱液氮（LN 2）较好的真空度。 </li></ol></li><li>重新填充有惰性气体的烧瓶（并继续流动气体在样品），并升高温度至320℃。该溶液应该打开清楚它加热，并在烧瓶壁过量固体可以通过在烧瓶小心旋流收集。 </li><li>冷却回落到120℃，并在真空下脱气如在步骤1.2.4。 </li><li>笔芯和再加热烧瓶步骤1.2.5。 </li><li>注入1.5克顶部进入通过隔膜烧瓶中。使溶液温度继续之前在340℃稳定。 注:尽量减少空气/湿气通过保持在惰性气氛下的隔膜小瓶的顶部，并尽可能快地注入其注入量。 </li><li>注入TOP:•混合物到烧瓶中通过隔膜，使用宽针注入TOP:作为快速且均匀š越好。启动计时器。 </li><li>注射后上方正好20秒:S，注入TOP:的CdSe混合物到烧瓶中通过隔膜，使用宽针注入TOP:的CdSe作为快速且均匀越好。 注:温度应该由这点低于330℃下降到由于加入的RT TOP溶液。 </li><li>设定温度至320℃，并让反应继续进行所需时间（8-15分钟），并从加热套除去。 </li><li>让反应从加热套的冷却程Ð当温度达到大约100℃注入约5毫升脱气的甲苯中。转移溶液至小瓶惰性气氛下进行清洁。 注意:为了简化此过程10ml甲苯可以放置在20ml的小瓶在惰性气体的恒定流动的隔片。使用大约一半的甲苯，注入到冷却的混合物，然后将冷却的混合物转移回该小瓶中。 </li><li>棒清洗<ol><li>放入50毫升的离心管中的溶液。 </li><li>加甲醇（约5毫升）以沉淀出从甲苯混合物的种子。 </li><li>离心3,400 XG 5分钟。 </li><li>倒出上层清液，并在大约10毫升己烷重新溶解沉淀。 </li><li>加1-2毫升每个正辛胺和壬酸的溶液。该解决方案应该是透明的。 </li><li>加入5毫升甲醇和离心3,400×g下5分钟。 </li><li>重复步骤2.3.13.4通过2.3.13.6至少两次以上。 </li><li>在10ml甲苯中再溶解沉淀。如果沉淀不容易溶解，有可能需要更多的清洗步骤，在这种情况下，重复步骤2.3.13.4通过2.3.13.6。 </li><li>加大约7毫升异丙醇，加入1ml的时间，直至溶液混合，即使稍微混浊。 </li><li>离心以便从一切分开较长杆为2200 xg离心30分钟。 </li><li>再溶于10-15毫升甲苯沉淀。 </li></ol></li><li>稀释在甲苯中的种子中的一小等分试样以测量杆的紫外 - 可见吸收和/或光致发光（PL）。 注意:任何等份体积是可接受的，只要该稀释因子是已知的，然而，典型的稀释因子将是20。PL，吸收应等于或低于0.1在选定的激发波长（通常使用450纳米）。 </li></ol></li></ol> 3.晶种棒转移到水溶液<ol><li>准备工作甲醇溶液定量<ol><li>倾约10毫升甲醇入离心管中。 </li><li>加约250毫克的巯基十一酸（MUA）和400毫克氢氧化四甲铵（TMAH）。 </li><li>涡或让坐在直到所有的固体完全溶解。 </li></ol></li><li>配体交换<ol><li>加甲醇（5-10毫升，或足以沉淀杆），以¼从步骤2中的离心管合成杆的半。 注意:用于将依赖于甲苯的量杆的体积用于溶解用于存储的棒。如果使用10-15毫升作为步骤2.3.13.11建议，然后3-6毫升杆溶液要适当。 </li><li>离心3,400 XG 5分钟。 </li><li>弃去上清液。 </li><li>从3.1节到颗粒加入所有的甲醇溶液。 </li><li>旋涡或震动用手充分溶解。让溶液坐至少1小时以允许发生最大配体交换。 ñOTE:该溶液应静置至少1小时，即使它似乎立即和完全溶解</li><li>分离溶液进入两个离心管两半。 注:保存用于步骤3.1的离心管中，转移一半溶液加入到那里。 </li><li> 20ml甲苯添加到每个一半。如果存在醇与甲苯之间的相分离加甲醇逐滴直到相复合。 </li><li>离心7700 XG 15分钟。 </li><li>非常小心地倒出从颗粒的上层清液。 </li><li>小心倒置离心管，以干燥样品。 </li><li> 5毫升超纯水加入沉淀和储存在小瓶中铝箔（或其他不透明覆盖物）缠好。 注意:一旦移动从甲苯到水，杆不耐光的，这就是为什么它们都包括在内。即使保持在黑暗中的棒应尽快使用，并且不建议存储棒在水中超过一个月。 </li></ol></li></ol> 4.成长铱纳米粒子<ol><li>氢氧化钠<ol><li>在一个塑料小瓶中称出1450毫克氢氧化钠。在20ml超纯水中溶解的NaOH。解决方案应该是无固体清楚。 </li></ol></li><li>过硫酸钠<ol><li>在一个塑料小瓶中称出950毫克的钠硫2 O 8。钠硫溶解2 O 8在20毫升超纯水。解决方案应该是无固体清楚。 </li></ol></li><li>硝酸钠<ol><li>在一个塑料小瓶中称出300毫克的亚硝酸钠3.溶解硝酸钠的18ml超纯水。解决方案应该是无固体清楚。 </li></ol></li><li>铱前体解决方案<ol><li>在一个塑料瓶中称出50毫克的Na 3 IrCl 6。溶解的Na 3 IrCl 6与5.0mL超纯水。解决方案应该是透明的棕色（如苏格兰威士忌），无固体。 </li></ol></li><li>预样品paration <ol><li>放置在一个标准聚苯乙烯比色皿的分光搅拌器。 注意:由于该解决方案是非常基本的，石英等玻璃试管，不应使用。 </li><li>添加从步骤4.4.10.20毫升铱前体溶液。 </li><li>加入0.50毫升硝酸盐溶液从步骤4.3.1。 </li><li>在水中加0.30ml接种棒从第3（跟踪从配体交换甲苯可能引起试管壁上的混浊）。 </li><li>从步骤4.2.1添加0.50毫升过的解决方案。 </li><li>从步骤4.1.1添加0.50毫升的氢氧化钠溶液中。 </li></ol></li><li>样品照明<ol><li>放置反应杯在搅拌能力的保持器。 </li><li> 450纳米的光在100毫瓦长达4小时的照明。该解决方案应该变绿后蓝色。 </li></ol></li><li>采集样品<ol><li>倾溶液（但不搅拌棒）到离心管中。 </li><li>离心7700 XG 10分钟。 </li><li>关心从粒料，这应该是绿色或蓝色根据所选择的反应时间充分倒出上清液。 注:沉淀现在可以收集或通过超声处理分散在极性溶剂中在其它实验。 </li></ol></li></ol>

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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photocatalytic+Hydrogen+Production+with+Tunable+Nanorod+Heterostructures.">Photocatalytic Hydrogen Production with Tunable Nanorod Heterostructures.</a> J. Phys. Chem. Lett. 1 (7), 1051-1054 (2010).</li><li>Nakibli, Y., Kalisman, P., Amirav, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Less+Is+More:+The+Case+of+Metal+Cocatalysts.">Less Is More: The Case of Metal Cocatalysts.</a> J. Phys. Chem. Lett. 6, 2265-2268 (2015).</li><li>Lupo, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+Electron-Hole+Dynamics+in+Core/Shell+CdSe/CdS+Dot/Rod+Nanocrystals.">Ultrafast Electron-Hole Dynamics in Core/Shell CdSe/CdS Dot/Rod Nanocrystals.</a> Nano Lett. 8 (12), 4582-4587 (2008).</li><li>Raino, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+the+Wave+Function+Delocalization+in+CdSe/CdS+Dot-in-Rod+Nanocrystals+by+Time-+and+Temperature-Resolved+Spectroscopy.">Probing the Wave Function Delocalization in CdSe/CdS Dot-in-Rod Nanocrystals by Time- and Temperature-Resolved Spectroscopy.</a> ACS Nano. 5 (5), 4031-4036 (2011).</li><li>Talapin, D. V., Lee, J. S., Kovalenko, M. V., Shevchenko, E. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospects+of+Colloidal+Nanocrystals+for+Electronic+and+Optoelectronic+Applications.">Prospects of Colloidal Nanocrystals for Electronic and Optoelectronic Applications.</a> Chem. Rev. 110 (1), 389-458 (2010).</li><li>Kraus, R. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room-Temperature+Exciton+Storage+in+Elongated+Semiconductor+Nanocrystals.">Room-Temperature Exciton Storage in Elongated Semiconductor Nanocrystals.</a> Phys. Rev. Lett. 98 (1), 017401 (2007).</li><li>She, C., Demorti&#232;re, A., Shevchenko, E. V., Pelton, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+Shape+to+Control+Photoluminescence+from+CdSe/CdS+Core/Shell+Nanorods.">Using Shape to Control Photoluminescence from CdSe/CdS Core/Shell Nanorods.</a> J. Phys. Chem. Lett. 2 (12), 1469-1475 (2011).</li><li>Manthiram, K., Beberwyck, B. J., Talapin, D. V., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seeded+Synthesis+of+CdSe/CdS+Rod+and+Tetrapod+Nanocrystals.">Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals.</a> J. Vis. Exp. (82), (2013).</li><li>Yu, W. W., Qu, L., Guo, W., Peng, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Determination+of+the+Extinction+Coefficient+of+CdTe,+CdSe,+and+CdS+Nanocrystals.">Experimental Determination of the Extinction Coefficient of CdTe, CdSe, and CdS Nanocrystals.</a> Chem. Mater. 15 (14), 2854-2860 (2003).</li><li>Miao, M. S., Seshadri, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rh2O3+versus+IrO2:+relativistic+effects+and+the+stability+of+Ir4.">Rh2O3 versus IrO2: relativistic effects and the stability of Ir4.</a> J. Phys. Condens. Matter. 24 (21), 215503 (2012).</li><li>Amirav, L., Alivisatos, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Luminescence+Studies+of+Individual+Quantum+Dot+Photocatalysts.">Luminescence Studies of Individual Quantum Dot Photocatalysts.</a> J. Am. Chem. Soc. 135 (35), 13049-13053 (2013).</li><li>Vaneski, A., Schneider, J., Susha, A. S., Rogach, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aqueous+synthesis+of+CdS+and+CdSe/CdS+tetrapods+for+photocatalytic+hydrogen+generation.">Aqueous synthesis of CdS and CdSe/CdS tetrapods for photocatalytic hydrogen generation.</a> APL Materials. 2 (1), 012104 (2014).</li></ol>

作者什么都没有透露。

硒化镉种子和硒化镉硫化镉@播种棒的合成已得到很好的研究21,24,25。轻微的修改的量，温度和时间对这些基材颗粒的合成的步骤可用于调整其长度，直径和/或形态。本文所描述的合成方案产生均匀尺寸的高度发光种子棒。 该配体交换过程允许使用在极性环境中接种棒，在这种情况下的水。在配体交换，当正在收集溶解丸粒（由甲苯沉淀后）的最终阶段的沉淀往往较?...

光催化提出了可再生能源发电和其他环境的应用，如水处理和空气净化1-3的吸引力和有前景的解决方案。总体水分解，利用太阳能驱动，可能是清洁和可再生氢燃料的来源;然而，尽管数十年的研究，这是足够稳定和有效的，对实际使用的系统尚未实现。 既光化学淀积和半导体介导的光催化依靠分离光生电子 - 空穴对，并将它们驱动到表面在那里他们可以引发氧化还原反应的相同的机制。这两个过程之间的相似性使得光化学淀积为光催化4-6领域一个有吸引力的合成工具。这种方法有望采取光触媒生产新的未知领域。这也许可能提供纯净的控制空间布局在异质结构的不同组件，以及前进到构造复杂的纳米颗粒系统的能力。最终，该方法将使我们更接近了一步实现直接太阳能到燃料能量转换的高效光催化剂。 我们研究的IrO 2的生长作为助催化剂，因为它是已知可用于水氧化7-11的高效催化剂。嵌入在杆（硫化镉）12,13量子点（硒化镉）的可调结构作为我们的光触媒基板14,15。它是目前待定是否经由介导的途径发生氧化途径，或通过直接孔攻击。在这里，我们对半导体异质结构的光生空穴了解和控制，可以用来达到氧化反应的机理研究。这是通过在衬底结构，这有利于密闭小孔16,17和地层的本地化成为可能在杆不同的氧化反应部位。纳米材料的局限性电荷载体的使用可以利用用于由产品的简单检查的氧化还原反应的机理研究。以这种方式光化学淀积可以用作两个还原和氧化反应途径的独特探针。这是通过光化学淀积和尖端胶体合成18-20的结合所带来的新的和令人兴奋的可能性的一个例子。 制定水分解和可再生能源转化的高效催化剂的追求已成为材料界的重要推力。这促使在硫化镉世界范围的兴趣，这是已知的生产氢的高活性，尽管它是由光化学不稳定的阻碍。我们这里的工作把材料的阿喀琉斯之踵。 2的IrO装饰的CdSe @硫化镉棒展示纯延长光照下显着的光化学稳定性水。

<table><tbody><tr><td>Sulfur (S)</td><td>Sigma</td><td>84683</td><td></td></tr><tr><td>Selenium (Se)</td><td>Sigma</td><td>229865</td><td></td></tr><tr><td>Cadmium Oxide (CdO)</td><td>Sigma</td><td>202894</td><td>Highly Toxic</td></tr><tr><td>n-Octadecylphosphonic acid (ODPA)</td><td>Sigma</td><td>715166</td><td></td></tr><tr><td>Propylphosphonic acid (PPA)</td><td>Sigma</td><td>305685</td><td>Highly regulated in some countries and regions</td></tr><tr><td>Butylphosphonic acid (BPA)</td><td>Sigma</td><td>737933</td><td>Alternative to PPA</td></tr><tr><td>Hexylphosphonic acid (HPA)</td><td>Sigma</td><td>750034</td><td>Alternative to PPA</td></tr><tr><td>Trioctylphosphonic oxide (TOPO)</td><td>Sigma</td><td>346187</td><td></td></tr><tr><td>Tri-n-octylphosphine, 97% (TOP)</td><td>Sigma</td><td>718165</td><td>Air sensitive</td></tr><tr><td>Spectrochemical Stirbar</td><td>Sigma</td><td>Z363545</td><td></td></tr><tr><td>Sodium Hydroxide</td><td>Sigma</td><td>S5881</td><td></td></tr><tr><td>Methanol</td><td>Sigma</td><td>322415</td><td></td></tr><tr><td>Toluene</td><td>Sigma</td><td>244511</td><td></td></tr><tr><td>Hexane</td><td>Sigma</td><td>296090</td><td></td></tr><tr><td>Octylamine</td><td>Sigma</td><td>74988</td><td></td></tr><tr><td>Nonanoic Acid</td><td>Sigma</td><td>N5502</td><td></td></tr><tr><td>Isopropanol</td><td>Sigma</td><td>278475</td><td></td></tr><tr><td>Mercaptoundecanoic Acid (MUA)</td><td>Sigma</td><td>674427</td><td></td></tr><tr><td>Tetramethylammonium Hydroxide (TMAH)</td><td>Sigma</td><td>T7505</td><td></td></tr><tr><td>Apiezon H Grease (high temperature grease)</td><td>Sigma</td><td>Z273562</td><td></td></tr><tr><td>Sodium Persulfate</td><td>Sigma</td><td>216232</td><td></td></tr><tr><td>Sodium Nitrate</td><td>Sigma</td><td>229938</td><td></td></tr><tr><td>Sodium Hexachloroiridate(III) hydrate</td><td>Sigma</td><td>288160</td><td></td></tr><tr><td>Mounted 455 nm LED</td><td>Thorlabs</td><td>M455L3</td><td></td></tr><tr><td>Cuvette Holder</td><td>Thorlabs</td><td>CVH100</td><td></td></tr><tr><td>25 ml 3-neck Round Bottom Flask</td><td>Chemglass</td><td>CG-1524-A-02</td><td></td></tr><tr><td>Liebig Condensor</td><td>Chemglass</td><td>CG-1218-A-20</td><td></td></tr><tr><td>T-Joint Adapter</td><td>Chemglass</td><td>AF-0509-10</td><td></td></tr></tbody></table>

photochemical oxidative growth of iridium oxide nanoparticles on cdse@cds nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

透射电子显微照片（TEM），以看到氧化铱的上引晶棒（图1）的分布收集。 TEM样品通过吹打溶解颗粒的下降到TEM网格制备。 X射线衍射（XRD， 图2）和 X射线光电子能谱（XPS，图3）被用来表征观察的生长结晶的IrO 2的混合和铱2 O 3等。 X射线衍射和XPS的样品的制备是通过在载玻片上的粒子的干燥完成。用足够的采?...

Watch this Scientific Journal Video about Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods at JoVE.com

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

铱氧化物纳米颗粒对硒化镉硫化镉@纳米棒光化学氧化增长

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

photochemical-oxidative-growth-iridium-oxide-nanoparticles-on-cdsecds

Research

JoVE Journal

Chemistry

9.5K 次观看.  Technion – Israel Institute of Technology. A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

视频: Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

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.

紧凑型量子点的单分子成像

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

科研

工程学

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.

通过电荷分离纳米晶及其固体收获太阳能

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

Revealing Dynamic Processes of Materials in Liquids Using Liquid Cell Transmission Electron Microscopy

The recent development for in situ transmission electron microscopy, which allows imaging through liquids with high spatial resolution, has attracted significant interests across the research fields of materials science, physics, chemistry and biology. The key enabling technology is a liquid cell. We fabricate liquid cells with thin viewing windows through a sequential microfabrication process, including silicon nitride membrane deposition, photolithographic patterning, wafer etching, cell bonding, etc. A liquid cell with the dimensions of a regular TEM grid can fit in any standard TEM sample holder. About 100 nanoliters reaction solution is loaded into the reservoirs and about 30 picoliters liquid is drawn into the viewing windows by capillary force. Subsequently, the cell is sealed and loaded into a microscope for in situ imaging. Inside the TEM, the electron beam goes through the thin liquid layer sandwiched between two silicon nitride membranes. Dynamic processes of nanoparticles in liquids, such as nucleation and growth of nanocrystals, diffusion and assembly of nanoparticles, etc., have been imaged in real time with sub-nanometer resolution. We have also applied this method to other research areas, e.g., imaging proteins in water. Liquid cell TEM is poised to play a major role in revealing dynamic processes of materials in their working environments. It may also bring high impact in the study of biological processes in their native environment.

We have developed a self-contained liquid cell, which allows imaging through liquids using a transmission electron microscope. Dynamic processes of nanoparticles in liquids can be revealed in real time with sub-nanometer resolution.

在液体中使用液体池透射电子显微镜揭示材料的动态过程

The recent development for in situ transmission electron microscopy, which allows imaging through liquids with high spatial resolution, has attracted ...

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.

硒化镉/硫化镉棒和纳米四脚合成种子

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

化学

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.

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.

a硫磺共聚物基质内的免费配体硫化镉纳米粒子的合成

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

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

金纳米棒基于对苯二酚合成

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are composed of CdSSe branches grown on ZnO nanowires that are vertically aligned on a transparent sapphire substrate. The morphology was measured via scanning electron microscopy. The crystal structure was determined by X-ray powder diffraction analysis. Both the ZnO stem and CdSSe branches have a predominantly wurtzite crystal structure. The mole ratio of S and Se in the CdSSe branches was measured by energy dispersive X-ray spectroscopy. The CdSSe branches result in strong visible light absorption. Photoluminescence (PL) spectroscopy showed that the stem and branches form a type-II heterojunction. PL lifetime measurements showed a decrease in the lifetime of emission from the trees when compared to emission from individual ZnO stems or CdSSe branches and indicate fast charge transfer between CdSSe and ZnO. The vertically aligned ZnO stems provide a direct electron transport pathway to the substrate and allow for efficient charge separation after photoexcitation by visible light. The combination of the abovementioned properties makes ZnO/CdSSe nanotrees promising candidates for applications in solar cells, photocatalysis, and opto-electronic devices.

Here, we prepare and characterize novel tree-like hierarchical ZnO/CdSSe nanostructures, where CdSSe branches are grown on vertically aligned ZnO nanowires. The resulting nanotrees are a potential material for solar energy conversion and other opto-electronic devices.

分层的ZnO / CdSSe异质Nanotrees的合成

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are ...

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.

形状-各向异性胶体镉硫纳米结构的 Facet-to-facet 连接

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

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.

配体介导成核与钯金属纳米粒子的生长

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

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic nanoparticles is developed. Guidelines for the replication of the reactor and its operation are provided in detail. Three different composite systems (Pt/graphene, Pt/TiO2, and Au/TiO2) with monodisperse and uniformly distributed particles are produced by this reactor, and the photodeposition mechanism, as well as the synthesis optimization strategy, are discussed. The synthesis methods and their technical aspects are described comprehensively. The role of the ultraviolet (UV) dose (in each excitation pulse) on the photodeposition process is investigated and the optimum values for each composite system are provided.

For a continuous and scalable synthesis of noble-metal-based nanocomposites, a novel photocatalytic reactor is developed and its structure, operation principles, and product quality optimization strategies are described.