Faceted Colloidal Au/Fe₃O₄ Binary Supracrystals Dictated by Intrinsic Lattice Structures and Their Collective Optical Properties

This is the authors' abstract. We don't add key points for this paper.

Although self-assembly of binary nanocrystal mixtures into long-range ordered crystalline films with tunable lattice structures are well-known, it would be interesting to shape these binary nanocrystal supracrystals into faceted assemblies because it potentially provides the shape-dependent optical, electronic, and catalytic properties. Herein, we report the self-assembly of binary nanocrystal supracrystals with faceted morphologies from Fe 3 O 4 and Au binary mixtures. The asymmetric crystal parameters in AlB 2 -type structure, a = b > c, favors one-dimensional (1D) self-assembly along the ⟨001⟩ direction, resulting in the formation of supraspindles and suprarods with 20 facets. For the symmetric cubic lattice system, like NaCl-type and NaZn 13 -type structures, truncated cube/octahedron with preferential exposed facets of (100) and (111) are produced. By contrast, for another cubic lattice of bcc -AB 6, in which large nanocrystals are ordered into body-centered-cubic ( bcc ) structure, truncated rhombic dodecahedra enclosed with (110) and (100) are made. The shape-controlled assembly of binary nanocrystal supracrystals composed of plasmonic Au nanocrystals enables engineering the plasmonic near field coupling in binary nanocrystal supracrystals dispersed in water.