Time-Resolved In Situ Synchrotron X-ray Study and Large-Scale Production of Magnetite Nanoparticles in Supercritical Water
Time-Resolved In Situ Synchrotron X-ray Study and Large-Scale Production of Magnetite Nanoparticles in Supercritical Water
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DOI：
10.1002/anie.200901048
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Iversen, Bo B.
中科院分区：
文献类型：
--
作者：
Bremholm, Martin;Felicissimo, Marcella;Iversen, Bo B.
纳米材料由于其尺寸相关的特性而具有关键重要性，这些特性提供了新的技术应用。金属纳米颗粒的磁性已经被深入研究，因为它们对超高密度存储介质的发展，[1]生物医学应用，[2]磁引导药物输送[3]和磁场癌症治疗的影响。[4，5]氧化铁磁性纳米颗粒特别令人感兴趣，因为它们是生物相容的并且具有低毒性。[6]磁性纳米颗粒可以通过几种方法合成，[7-10]并且已经实现了对粒度和粒度分布的控制。然而，与大规模生产相关的挑战，例如有机溶剂的使用，纳米颗粒的相纯度和长反应时间，仍然存在。[11]在近临界（nc）和超临界（sc）水中进行的纳米粒子合成的原位研究提供了一个特殊的机会，以了解和优化在环境友好的介质中以高生产率生产纳米粒子。nc-H2O和sc-H2O合成最吸引人的特征是通过简单地改变压力、温度和停留时间来调节颗粒尺寸和形态的可能性。金属前驱体在超临界介质中的热分解导致高的成核速率，这导致小的初级团簇的形成。[12]我们专注于使用分析工具，能够在真实的时间以下的纳米粒子的形成和生长。原位衍射研究特别适合于实现这一目标，[13-15]但在超临界流体条件下的原位研究仍然很少。我们最近报道了第一次原位研究sc-CO2（Pc= 74巴，Tc= 318 C）的形成二氧化钛通过使用同时小角和广角X射线散射（SAXS/WAXS）。[16]时间分辨SAXS/WAXS是能够确定粒度、粒度分布、形态和结晶度的互补方法。这些研究还提供
Nanomaterials are of key importance owing to their dimension-dependent properties that provide novel technological applications. The magnetic properties of metal nanoparticles have been intensively explored due to their impact on the development of ultra-high-density storage media,[1] biomedical applications,[2] magnetically guided drug delivery,[3] and magnetic field cancer therapy.[4, 5] Iron oxide magnetic nanoparticles are of particular interest since they are biocompatible and have low toxicity.[6]Magnetic nanoparticles can be synthesized by several methods,[7–10] and control of particle size and particle-size distribution has been achieved. However, challenges associated with large-scale production, such as the use of organic solvents, phase purity of the nanoparticles, and long reaction times, remain.[11] In situ studies on the synthesis of nanoparticles performed in near-critical (nc) and supercritical (sc) water provide an exceptional opportunity to understand and optimize the production of nanoparticles in an environmentally friendly medium with high production rates. The most attractive feature of nc-H2O and sc-H2O synthesis is the possibility to tune the particle size and morphology by simply varying the pressure, temperature, and residence time. The thermal decomposition of metal precursors in a supercritical medium leads to high nucleation rates, which lead to the formation of small primary clusters.[12] We focus on the use of analytical tools capable of following nanoparticle formation and growth in real time. In situ diffraction studies are particularly suitable to achieve this goal,[13–15] but in situ studies under supercritical fluid conditions remain rare. We recently reported the first in situ study in sc-CO2 (Pc= 74 bar, Tc= 318C) on the formation of TiO2 by using simultaneous small-and wide-angle X-ray scattering (SAXS/WAXS).[16] Time-resolved SAXS/WAXS are complementary methods that enable determination of particle size, size distribution, morphology, and crystallinity. These studies also offer