How "hollow" are hollow nanoparticles?
How "hollow" are hollow nanoparticles?
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DOI：
10.1021/ja311926r
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发表时间：
2013-02
影响因子：
15
通讯作者：
P. Podsiadlo;S. Kwon;Bon‐Ryul Koo;Byeongdu Lee;V. Prakapenka;P. Dera;K. Zhuravlev;Galyna Krylova
中科院分区：
文献类型：
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作者：
P. Podsiadlo;S. Kwon;Bon‐Ryul Koo;Byeongdu Lee;V. Prakapenka;P. Dera;K. Zhuravlev;Galyna Krylova
采用金刚石顶压室、同步辐射X射线衍射仪和小角X射线散射仪对空心γ-Fe(3)O(4)纳米颗粒(NPs)的成分进行了研究。对5·2、13·3和13·8 nm空壳γ-Fe(3)O(4)纳米粒子和6 nm核/14·8 nm空壳Au/Fe(3)O(4)纳米粒子的SAXS实验表明，空壳内部的电子密度显著高于溶剂。在以Ne为传压介质的高压DAC实验中，X射线衍射仪没有检测到中空纳米粒子内部有纳米晶Ne的形成，这表明氧化层是不可穿透的。此外，对回流破碎的空壳γ-Fe(3)O(4)纳米颗粒溶液的傅里叶变换红外光谱分析表明，没有证据表明有机分子来自空隙中，排除了有机分子在合成过程中穿过氧化铁壳的可能性。对Au/Fe(3)O(4)核/中空壳NPs的高压DAC实验表明，外压对金核的透过率很好，表明在核与中空壳之间的缝隙中存在着传压介质。总体而言，我们的数据显示，在中空NPs的空隙中最有可能存在铁和/或氧化铁的小碎片。氧化铁外壳似乎是无孔的，气体和液体无法穿透。
Diamond anvil cell (DAC), synchrotron X-ray diffraction (XRD), and small-angle X-ray scattering (SAXS) techniques are used to probe the composition inside hollow γ-Fe(3)O(4) nanoparticles (NPs). SAXS experiments on 5.2, 13.3, and 13.8 nm hollow-shell γ-Fe(3)O(4) NPs, and 6 nm core/14.8 nm hollow-shell Au/Fe(3)O(4) NPs, reveal the significantly high (higher than solvent) electron density of the void inside the hollow shell. In high-pressure DAC experiments using Ne as pressure-transmitting medium, formation of nanocrystalline Ne inside hollow NPs is not detected by XRD, indicating that the oxide shell is impenetrable. Also, FTIR analysis on solutions of hollow-shell γ-Fe(3)O(4) NPs fragmented upon refluxing shows no evidence of organic molecules from the void inside, excluding the possibility that organic molecules get through the iron oxide shell during synthesis. High-pressure DAC experiments on Au/Fe(3)O(4) core/hollow-shell NPs show good transmittance of the external pressure to the gold core, indicating the presence of the pressure-transmitting medium in the gap between the core and the hollow shell. Overall, our data reveal the presence of most likely small fragments of iron and/or iron oxide in the void of the hollow NPs. The iron oxide shell seems to be non-porous and impenetrable by gases and liquids.