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
Summary
A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.
Abstract
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).
Introduction
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。
Protocol
Representative Results
Discussion
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?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
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。
Materials
| Sulfur (S) | Sigma | 84683 | |
| Selenium (Se) | Sigma | 229865 | |
| Cadmium Oxide (CdO) | Sigma | 202894 | Highly Toxic |
| n-Octadecylphosphonic acid (ODPA) | Sigma | 715166 | |
| Propylphosphonic acid (PPA) | Sigma | 305685 | Highly regulated in some countries and regions |
| Butylphosphonic acid (BPA) | Sigma | 737933 | Alternative to PPA |
| Hexylphosphonic acid (HPA) | Sigma | 750034 | Alternative to PPA |
| Trioctylphosphonic oxide (TOPO) | Sigma | 346187 | |
| Tri-n-octylphosphine, 97% (TOP) | Sigma | 718165 | Air sensitive |
| Spectrochemical Stirbar | Sigma | Z363545 | |
| Sodium Hydroxide | Sigma | S5881 | |
| Methanol | Sigma | 322415 | |
| Toluene | Sigma | 244511 | |
| Hexane | Sigma | 296090 | |
| Octylamine | Sigma | 74988 | |
| Nonanoic Acid | Sigma | N5502 | |
| Isopropanol | Sigma | 278475 | |
| Mercaptoundecanoic Acid (MUA) | Sigma | 674427 | |
| Tetramethylammonium Hydroxide (TMAH) | Sigma | T7505 | |
| Apiezon H Grease (high temperature grease) | Sigma | Z273562 | |
| Sodium Persulfate | Sigma | 216232 | |
| Sodium Nitrate | Sigma | 229938 | |
| Sodium Hexachloroiridate(III) hydrate | Sigma | 288160 | |
| Mounted 455nm LED | Thorlabs | M455L3 | |
| Cuvette Holder | Thorlabs | CVH100 | |
| 25mL 3-neck Round Bottom Flask | Chemglass | CG-1524-A-02 | |
| Liebig Condensor | Chemglass | CG-1218-A-20 | |
| T-Joint Adapter | Chemglass | AF-0509-10 |
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