MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology , Harbin, Heilongjiang 150001, China.
ACS Nano. 2017 Jun 27;11(6):6370-6381. doi: 10.1021/acsnano.7b02752. Epub 2017 Jun 15.
Magnetite (FeO) nanocrystals (MNCs) are among the most-studied magnetic nanomaterials, and many reports of solution-phase synthesis of monodisperse MNCs have been published. However, lack of reproducibility of MNC synthesis is a persistent problem, and the keys to producing monodisperse MNCs remain elusive. Here, we define and explore synthesis parameters in this system thoroughly to reveal their effects on the product MNCs. We demonstrate the essential role of benzaldehyde and benzyl benzoate produced by oxidation of benzyl ether, the solvent typically used for MNC synthesis, in producing monodisperse MNCs. This insight allowed us to develop stable formulas for producing monodisperse MNCs and propose a model to rationalize MNC size and shape evolution. Solvent polarity controls the MNC size, while short ligands shift the morphology from octahedral to cubic. We demonstrate preparation of specific assemblies with these MNCs. This standardized and reproducible synthesis of MNCs of well-controlled size, shape, and magnetic properties demonstrates a rational approach to stabilizing and expanding existing protocols for nanocrystal syntheses and may drive practical advances including enhanced MRI contrast, higher catalytic selectivity, and more accurate magnetic targeting.
磁铁矿 (FeO) 纳米晶体 (MNC) 是研究最多的磁性纳米材料之一，已有许多关于单相 MNC 溶液合成的报道。然而，MNC 合成的重复性差是一个长期存在的问题，产生单相 MNC 的关键仍然难以捉摸。在这里，我们彻底定义和探索了该体系中的合成参数，以揭示它们对产物 MNC 的影响。我们证明了苯甲醚氧化产生的苯甲醛和苯甲酸苄酯在产生单相 MNC 中的重要作用，苯甲醚通常是用于 MNC 合成的溶剂。这一见解使我们能够开发出生产单相 MNC 的稳定配方，并提出了一个模型来合理地解释 MNC 尺寸和形状的演变。溶剂极性控制 MNC 的尺寸，而短配体则将形态从八面体转变为立方体形。我们用这些 MNC 展示了特定组装体的制备。这种具有良好控制的尺寸、形状和磁性能的 MNC 的标准化和可重复的合成方法证明了一种稳定和扩展现有的纳米晶体合成协议的合理方法，并可能推动实际进展，包括增强 MRI 对比、更高的催化选择性和更准确的磁靶向。
