小角X射线散射
纳米棒
棒
材料科学
成核
对苯二酚
分散性
散射
相(物质)
化学物理
结晶学
分析化学(期刊)
化学工程
纳米技术
化学
光学
色谱法
物理
高分子化学
有机化学
病理
工程类
替代医学
医学
作者
Susanne Seibt,Heyou Zhang,Stephen Mudie,Stephan Foerster,Paul Mulvaney
标识
DOI:10.1021/acs.jpcc.1c06778
摘要
Using simultaneous, in situ optical spectroscopy and time-resolved, small-angle X-ray scattering (SAXS), we have directly monitored the seeded growth of nearly monodisperse gold nanorods using hydroquinone as the reductant. Growth of the rods is much slower than with the ascorbate ion, allowing the rate of growth along both the longitudinal and transverse directions to be independently determined. The thickness of the stabilizing CTAB layer (3.2 ± 0.3 nm) has also been extracted. We find that increasing the hydrogen tetrachloroaurate(III) concentration produces longer rods, while conversely, increasing the hydroquinone concentration reduces the final aspect ratio. The final number of gold rods is smaller than the initial number of seed particles and decreases in the presence of larger concentrations of HAuCl4. The SAXS data reveal an early transition from a spherical morphology to an ellipsoidal one and then to spherically capped cylinders. The growth curve exhibits at least three distinct regimes: an initial phase comprising spherical seed growth, followed by symmetry breaking and slow elongation. A third phase is marked by rapid rod growth and increases in the aspect ratio. This process is temporally well resolved from the initial symmetry breaking but typically occurs when the rods are around 6 nm in diameter using hydroquinone as the reductant. The results provide qualitative support for the “popcorn model” proposed by Edgar et al. [Formation of Gold Nanorods by a Stochastic “Popcorn” Mechanism. ACS Nano 2012, 6, 1116 1125].
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