Tuning the Growth Mode of 3D Silver Nanocrystal Superlattices by Triphenylphosphine

Abstract

International audienceHere, we show that the residual presence of reaction products markedly influences the growth mode of 3D superlattices made of silver nanocrystals. The silver nanocrystals (5 or 6 nm in diameter) are synthesized via the reduction of a silver triphenylphosphine complex in the presence of thiols. The presence of triphenylphosphine, coming from the decomposition of the silver precursor, is shown to change the superlattice growth mode in hexane from heterogeneous to homogeneous. In toluene, it remains homogeneous. This is in agreement with simulations based on a Flory-type model, which shows that the interaction potential between the silver nanocrystals in the presence of triphenylphosphine changes from repulsive to attractive in hexane and becomes even more attractive in toluene. Ex situ investigation of the different superlattices following solvent evaporation by scanning electron microscopy reveals different morphologies depending on the growth mode. A transition from films to individual hexagonal-shaped superlattices is observed when the growth mode changes from heterogeneous to homogeneous. Direct in situ observations of the 3D superlattice growth by liquid cell transmission electron microscopy follow in real time the formation process and movement of the superlattices in both hexane and toluene solvents

Versatile and robust synthesis process for the fine control of the chemical composition and core-crystallinity of spherical core–shell Au@Ag nanoparticles

“…Nevertheless, the SLs shapes are better defined, with the appearance of triangular shaped SLs, for higher NP sizes and for SC NPs. These well-defined shapes are characteristic of homogeneous growth in solution that could be favored by an increase in NP-NP interactions between larger NPs due to larger van der Waals interactions or between SC NPs due to the presence of larger facets [44,45]. Furthermore, previous results showed that the nature of the interactions between NPs (attractive or repulsive) depend both on the nature of the capping agent and the van der Waals attractions between the cores for a given solvent [44,45].…”

Nanoparticle Superlattices: The Roles of Soft Ligands

“…As the most commonly used ligands, alkylthiol (e.g., propanethiol, hexanethiol, decanethiol, dodecanethiol, and hexadecanethiol, etc.) has been used to rationally construct 2D hexagonal closely packed superlattices and 3D superlattices with various lattice structures. With the right control over the superlattice assembly kinetics such as flux of particles into the interface ( f ) and interfacial diffusion length (δ), it is possible to form 2D freestanding superlattice membranes …”

Light Driven Design of Dynamical Thermosensitive Plasmonic Superstructures: A Bottom-Up Approach Using Silver Supercrystals

“…On the one hand, if a very poor solvent, such as toluene, is used, one can hardly disperse the particles in solution, as they easily form large SCs and precipitate, even before laser light illumination. On the other hand, in mixture of poor and good solvents a compromise between limiting NP aggregation (toluene, poor solvent) and solubilization (hexane, good solvent) , can be reached, resulting in the formation of SCs (consisting of arrangement of NPs). Prior environmental transmission electron microscopy (TEM) studies have shown that, in 60% toluene, SCs of radius of ∼100–300 nm spontaneously form in solution.…”

“…Herein, a proof of concept of this idea is provided. Narrowly distributed 5.9 ±0.4 nm silver NPs that are capped with dodecanethiol (C 12 AgNP) spontaneously organize in organic solvents into nanometric SCs . The interaction of the C 12 chains with the solvent also generate migration toward the laser beam, driving the SCs together under the laser spot, forming a micrometric aggregate, as indicated in Figure A.…”