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首页> 外文期刊>Physical chemistry chemical physics: PCCP >An in situ quick XAFS spectroscopy study on the formation mechanism of small gold nanoparticles supported by porphyrin-cored tetradentate passivants
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An in situ quick XAFS spectroscopy study on the formation mechanism of small gold nanoparticles supported by porphyrin-cored tetradentate passivants

机译：原位快速XAFS光谱研究以卟啉为核心的四齿钝化剂支撑的小金纳米颗粒的形成机理

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We previously reported that a porphyrin-cored tetradentate passivant, which has two disulfide straps over one face of the porphyrin plane, can produce monolayer-protected gold nanoparticles, 2-4 nm in size, by the one-pot reduction of HAuCl4 in DMF. The resulting nanoparticles are smaller than those prepared using the same S/Au molar ratio of a monodentate passivant. To examine the formation mechanism of small gold nanoparticles, the formation of gold nanoparticles in the presence of porphyrin-cored tetradentate passivants or a structurally related monodentate passivant was studied by time-resolved quick X-ray absorption fine structure spectroscopy. The results demonstrated that all of Au ions in solution are reduced to compose small Au clusters, i.e. nuclei, just after the NaBH4 reduction of HAuCl4 in both cases, but their size varied with the initial S/Au molar ratios and structure of the passivants. Thus, the size of Au nuclei was kinetically controlled by the passivants. Interestingly, the porphyrin-cored tetradentate passivant could stabilize smaller gold nanoparticles, 2-4 nm in size, but it was less efficient in trapping the Au nuclei formed at a very early stage, in comparison to the monodentate passivant.
机译：我们之前曾报道过，在卟啉平面的一面上具有两个二硫键的卟啉核芯四齿钝化剂可以通过在DMF中一锅还原HAuCl4来生产大小为2-4 nm的单层保护金纳米颗粒。所得纳米颗粒小于使用相同单齿钝化剂的S / Au摩尔比制备的纳米颗粒。为了检查小金纳米颗粒的形成机理，通过时间分辨快速X射线吸收精细结构光谱研究了以卟啉为核心的四齿钝化剂或结构相关的单齿钝化剂的存在下金纳米颗粒的形成。结果表明，在两种情况下，在NaBH4还原HAuCl4后，溶液中的所有Au离子都被还原成小的Au团簇，即原子核，但是它们的大小随初始S / Au摩尔比和钝化剂的结构而变化。因此，金原子核的大小由钝化剂动力学控制。有趣的是，以卟啉为核心的四齿钝化剂可以稳定尺寸为2-4 nm的较小金纳米颗粒，但与单齿钝化剂相比，它在捕获非常早期阶段形成的金核时效率较低。

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