School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332, USA.
The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, 30332, USA.
Chemistry. 2020 Dec 1;26(67):15636-15642. doi: 10.1002/chem.202003202. Epub 2020 Oct 28.
Oleic acid (OAc) is commonly used as a surfactant and/or solvent for the oil-phase synthesis of metal nanocrystals but its explicit roles are yet to be resolved. Here, we report a systematic study of this problem by focusing on a synthesis that simply involves heating of Pt(acac) in OAc for the generation of Pt nanocrystals. When heated at 80 °C, the ligand exchange between Pt(acac) and OAc leads to the formation of a Pt -oleate complex that serves as the actual precursor to Pt atoms. Upon increasing the temperature to 120 °C, the decarbonylation of OAc produces CO, which can act as a reducing agent for the generation of Pt atoms and thus formation of nuclei. Afterwards, several catalytic reactions can take place on the surface of the Pt nuclei to produce more CO, which also serves as a capping agent for the formation of Pt nanocrystals enclosed by {100} facets. The emergence of Pt nanocrystals further promotes the autocatalytic surface reduction of Pt precursor to enable the continuation of growth. This work not only elucidates the critical roles of OAc at different stages in a synthesis of Pt nanocrystals, but also represents a pivotal step forward toward the rational synthesis of metal nanocrystals.
油酸（OAc）通常用作金属纳米晶体油相合成的表面活性剂和/或溶剂，但它的明确作用尚未得到解决。在这里，我们通过聚焦于简单涉及在 OAc 中加热 Pt(acac)以生成 Pt 纳米晶体的合成来系统地研究这个问题。当在 80°C 加热时，Pt(acac)和 OAc 之间的配体交换导致形成 Pt-油酸配合物，该配合物充当 Pt 原子的实际前体。当温度升高到 120°C 时，OAc 的脱羰作用会产生 CO，CO 可以充当还原剂以生成 Pt 原子并因此形成核。之后，在 Pt 核的表面上可以发生几个催化反应，以产生更多的 CO，CO 还可以作为由 {100} 面封闭的 Pt 纳米晶体的封端剂。Pt 纳米晶体的出现进一步促进了 Pt 前体的自动催化表面还原，从而能够继续生长。这项工作不仅阐明了 OAc 在 Pt 纳米晶体合成的不同阶段的关键作用，而且代表了朝着金属纳米晶体的合理合成迈出的关键一步。
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