2D Binary Superlattices of Gold Nanoparticles

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Gold nanoparticle superlattice visuals
(a) 1x1 2D hexagonal lattices of AuNP grafted with PEG; (b) √3x√3 co-crystallization of two AuNP grafted with two distinct PEG.  The new binary structure is derived from the one shown in (a). (c) Schematic illustration on how the binary structure is formed by voids in the parent hexagonal structure.  
Scientific Achievement

Two distinct complex two-dimensional binary superlattices were self-assembled by co-crystallizing gold nanoparticles (AuNPs) of two distinct sizes. 

Significance and Impact

The packing density of mixed NP systems (binary, ternary, and higher order) can be tuned by manipulating their effective diameter by the choice of grafting. Such control enables designing self-assembled NPs in photonics and plasmonics applications.

Research Details
  • Grafting AuNPs with polyethylene glycol (PEG) at various lengths was confirmed by various techniques – DLS, UV-vis, TGA.  
  • Surface sensitive X-ray diffraction methods at NSLS-II are used to determine the structures of the assembly and co-crystallization.
  • The observed √3x√3 and 2x2 complex binary superlattices are derived from the hexagonal structures of the single components. 

Hyeong Jin Kim, Wenjie Wang, Honghu Zhang, Guillaume Freychet, Benjamin M. Ocko, Alex Travesset, Surya K. Mallapragada, and David Vaknin, "Binary Superlattices of Gold Nanoparticles in Two Dimensions," J. Phys. Chem. Lett. 2022, 13, 3424−3430.