High Resolution STEM-EELS Study of Silver Nanoparticles Exposed to Light and Humic Substances.
High Resolution STEM-EELS Study of Silver Nanoparticles Exposed to Light and Humic Substances.
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DOI：
10.1021/acs.est.5b04088
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发表时间：
2016-02
影响因子：
11.4
通讯作者：
I. Römer;Zhi Wang;R. Merrifield;R. Palmer;J. Lead
中科院分区：
文献类型：
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作者：
I. Römer;Zhi Wang;R. Merrifield;R. Palmer;J. Lead
纳米颗粒（NPs）被定义为具有至少一个在1和100 nm之间的尺寸或具有不同于其本体材料的性质的颗粒，其具有独特的性质。NP的广泛使用意味着向环境中的排放可能会增加，但在环境相关条件下的归宿，行为和影响尚未得到充分研究。本文主要研究银纳米粒子在模拟但真实的环境条件下的转化。高分辨率像差校正扫描透射电子显微镜（HAADF STEM）加上电子能量损失谱（EELS）和紫外-可见光在多方法的方法来研究形态，表面化学转化和电晕形成。尽管观察到损失（最有可能是溶解），但STEM-EELS中没有氧化的直接证据。然而，在富里酸（FA）的存在下，在水中的AgNP周围观察到1.3nm的含氧电晕;基于近原子分辨率的HAADF信号的建模数据表明，这是形成的FA电晕，而不是银氧化物，其是相干的（即，完全涂覆在FA中）。电晕进一步使NP胶体稳定数周至数月的时间，这取决于溶液条件。
Nanoparticles (NPs) are defined as particles with at least one dimension between 1 and 100 nm or with properties that differ from their bulk material, which possess unique properties. The extensive use of NPs means that discharge to the environment is likely increasing, but fate, behavior, and effects under environmentally relevant conditions are insufficiently studied. This paper focuses on the transformations of silver nanoparticles (AgNPs) under simulated but realistic environmental conditions. High resolution aberration-corrected scanning transmission electron microscopy (HAADF STEM) coupled with electron energy loss spectroscopy (EELS) and UV-vis were used within a multimethod approach to study morphology, surface chemistry transformations, and corona formation. Although loss, most likely by dissolution, was observed, there was no direct evidence of oxidation from the STEM-EELS. However, in the presence of fulvic acid (FA), a 1.3 nm oxygen-containing corona was observed around the AgNPs in water; modeled data based on the HAADF signal at near atomic resolution suggest this was an FA corona was formed and was not silver oxide, which was coherent (i.e., fully coated in FA), where observed. The corona further colloidally stabilized the NPs for periods of weeks to months, dependent on the solution conditions.