Synthesis and self-assembly study of metallic nanoparticles Ni Huo, Jiayang Hu, Irving P. Herman Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10025 [email protected]
The motivation is to design strategies to form targeted organizations via self-assembly of the nanoparticles into designed systems and reveal the governing effect, as well as design rational synthetic method for a series of metallic nanoparticles and quantum dots with different sizes and shapes.
Synthesis and mechanism study Iron oxide nanoparticles
Silver nanocubes (hydrophilic ligand)
SEM pictures of silver nanocubes (110nm)
Iron oxide NPs were synthesized using a hot-injection method, with iron pentacarbonyl injected into an oleic acid (OA)/octadecane mixture and maintained at 345 ℃ for 1h.
Silver nanocubes (hydrophobic ligand)
Ag NCs with hydrophobic ligands are more desirable for selfassembly study
TEM pictures of iron oxide NPs: a)6nm b)6.5nm c)8nm d)12nm
The NP size is controlled by OA/iron pentacarbonyl ratio. The NP dispersion was exposed to air for 30 min to transform the particles to magnetite.
The synthetic strategy of Ag NCs with oleate ligands mainly depends on the etching of multiply twinned NPs which later redeposited on more stable NPs.
Self- assembly experiment Experimental setup
Schlenk line system
2D SAXS result
Real time in-situ synchrotron small-angle X-ray scattering (SAXS) and in-situ optical microscopy are used to follow the formation of ordered iron oxide NP monolayers (MLs) and superlattices. Nanoparticle: 6-14nm Iron oxide Ligand: Oleate Upper solvent: Hexane / Heptane Lower solvent: Diethylene glycol
Alignment of the X-ray beam with the liquid surface for grazing incidence SAXS (GISAXS) by downstream monitoring of the transmitted X-ray beam as the cell moves with the stage. Surface separation(nm) 6
2D small angle X-ray scattering Table of Contents figure (SAXS)
In-situ optical microscopy
The cell was designed for observing the superlattice formation. The designed trapezoidal cross-section minimizes the impact of meniscus on the intensity data. FEP and Kapton film were used as the windows of the cell considering their X-ray attenuation coefficient and surface tension.
Time(s) 3 180
BNL NSLS II 11-beamline layout
SAXS images and the distance change of the core surfaces of nearest-neighbor iron oxide NPs(10nm) during the formation of a hexagonally ordered array.
Reference: Hu, J., Pan, B., Smith, E., Huo, N. & Herman, I. P. (2018). Time-Resolved and Space-Resolved Study of Iron Oxide Nanoparticle Self-Assembly on Liquid Surfaces by Using In-Situ Small Angle X-Ray Scattering. APS March Meeting 2018. American Physical Society.  Zhang, D., Lu, C., Hu, J., Lee, S. W., Ye, F., & Herman, I. P. (2015). Small angle x-ray scattering of iron oxide nanoparticle monolayers formed on a liquid surface. Journal of Physical Chemistry C, 119(19), 150421171632004.  Zhou, S., Li, J., Gilroy, K. D., Tao, J., Zhu, C., & Yang, X., et al. (2016). Facile synthesis of silver nanocubes with sharp corners and edges in an aqueous solution. Acs Nano, 10(11), 9861.  Peng, S., & Sun, Y. (2010). Synthesis of silver nanocubes in a hydrophobic binary organic solvent. Chemistry of Materials, 22(23), 6272-6279.