Li Mo, Li Xiangcun, Qi Xinhong, Luo Fan, He Gaohong
Langmuir. 2015 May 12;31(18):5190-7. doi: 10.1021/acs.langmuir.5b00800. Epub 2015 Apr 28.
The preparation of nonspherical magnetic core-shell nanostructures with uniform sizes still remains a challenge. In this study, magnetic iron oxide@SiO2-Au@C particles with different shapes, such as pseduocube, ellipsoid, and peanut, were synthesized using hematite as templates and precursors of magnetic iron oxide. The as-obtained magnetic particles demonstrated uniform sizes, shapes, and well-designed core-shell nanostructures. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analysis showed that the Au nanoparticles (AuNPs) of ∼6 nm were uniformly distributed between the silica and carbon layers. The embedding of the metal nanocrystals into the two different layers prevented the aggregation and reduced the loss of the metal nanocrystals during recycling. Catalytic performance of the peanut-like particles kept almost unchanged without a noticeable decrease in the reduction of 4-nitrophenol (4-NP) in 8 min even after 7 cycles, indicating excellent reusability of the particles. Moreover, the catalyst could be readily recycled magnetically after each reduction by an external magnetic field.
制备尺寸均匀的非球形磁性核壳纳米结构仍然是一项挑战。在本研究中，以赤铁矿为磁性氧化铁的模板和前驱体，合成了具有不同形状（如假立方体、椭球体和花生状）的磁性氧化铁@SiO₂-Au@C颗粒。所获得的磁性颗粒表现出均匀的尺寸、形状以及精心设计的核壳纳米结构。透射电子显微镜（TEM）和能量色散X射线光谱（EDX）分析表明，约6 nm的金纳米颗粒（AuNP）均匀分布在二氧化硅层和碳层之间。将金属纳米晶体嵌入两层不同的层中可防止其聚集，并减少回收过程中金属纳米晶体的损失。即使经过7个循环，花生状颗粒在8分钟内对4-硝基苯酚（4-NP）还原反应的催化性能几乎保持不变，没有明显下降，表明该颗粒具有出色的可重复使用性。此外，每次还原反应后，通过外部磁场可轻松地磁性回收催化剂。
