Primary growth of binary nanoparticle superlattices with distinct systems contingent on synergy: softness and crystalline anisotropy

Abstract

Binary nanoparticle superlattices (BNSLs), which are studied for developing multicomponent materials and multifunctional nanodevices, are distinguished by their outstanding synergetic properties. Owing to complex factors that might influence the formation of BNSLs, it is necessary to comprehensively explore the self-assembly of nanocrystals. A variety of BNSL structural configurations, such as NaZn13, Cu3Au, NaCl, AlB2, CaCu5-type structures, were obtained by cocrystallizing Au–Ni and Ag–Ni nanocrystals of different sizes. Specifically, at a similar effective size ratio, the supercrystal structures formed by the Au–Ni and Ag–Ni systems coated with different organic ligands are not essentially the same. We attribute this diversity to the different softness of effective entities and facet-dependent interdigitation between the ligands tethered on the nanoparticle surface. Inherent crystallinity directed formation of the final BNSL structures is likely driven by anisotropic or isotropic cocrystallization. The synergistic effect of the coating agent and crystallinity directed assembly process is reasonably believed to be the important factor affecting the growth of BNSLs, which provides a new idea for the study of kinetics during the self-assembly of supercrystals.