Gold nanoparticle superlattices: structure and cavities studied by GISAXS and PALS

Abstract

The performance of nanoparticle assemblies with respect to various applications (e.g. sensors, catalysts, filtration membranes) depends on their microporosity. Here, the microcavities within the ligand matrix of superlattice films comprised of 1-dodecanethiol-stabilized gold nanoparticles (GNPs, core diameter $4 and $5.5 nm) were studied by positron annihilation lifetime spectroscopy (PALS). The superlattice composition, the size and spatial arrangement of the GNP cores were characterized by thermogravimetric analysis, transmission electron microscopy and grazing-incidence small-angle X-rayscattering. From these data a structural model was derived to predict the sizes of the voids formed within the interstitial (tetrahedral and octahedral) sites of the superlattices. The comparison of the PALSmeasured cavity sizes (0.50 to 0.74 nm) with the predicted void sizes of the interstitial sites ($0.7 to $1.7 nm) and the free volume in solid dodecane (0.36 nm), previously measured by PALS, indicate that both types of cavities may contribute to the experimentally determined cavity sizes. However, the GNP core sizes had only a minor influence on the measured cavity size. Larger cavities with sizes corresponding to the voids ($1.7 nm) expected within the octahedral sites of the superlattices comprised of $5.5 nm-sized GNP cores could not be detected. Assuming the intensities arising from these voids are measurable, this finding suggests that the octahedral sites are occupied by excess ligands trapped during film preparation.Apart from the voids predicted for the interstitial sites, the larger cavity sizes measured for the GNP superlattices compared to crystalline dodecane may result from some degree of disorder in the ligand arrangement.

Size-Dependent Phase Transfer Functionalization of Gold Nanoparticles To Promote Well-Ordered Self-Assembly

“…The high degree of order was confirmed with SEM, TEM, and GISAXS measurements. The edge-to-edge distances determined by nearest-neighbor- and Fourier analysis of the SEM and TEM data and by refinement of the scattering data were in the range 1.6–2.0 nm, quite similar to values recently reported for superlattices from dodecanethiol-coated AuNP . For AuNP@OLAM with 6.4 nm core diameter, less order was observed.…”

“…The edge-to-edge distances determined by nearest-neighbor-and Fourier analysis of the SEM and TEM data and by refinement of the scattering data were in the range 1.6−2.0 nm, quite similar to values recently reported for superlattices from dodecanethiol-coated AuNP. 51 For AuNP@OLAM with 6.4 nm core diameter, less order was observed. The characterization of dropcasted AuNP@OLAM superstructures is provided as Supporting Information (Figure S1).…”

Effects of Lattice Evolution and Ordering on the Microwave Dielectric Properties of Tin-Modified Li3Mg2NbO6-Based Ceramics

“…These reflections may likewise be related to the formation of superlattices, and this phenomenon is in agreement with that quoted in the literature. 40,41 The TEM−EDS (energy dispersive spectroscopy) photographs for the samples of x = 0, x = 0.1, x = 0.2, and x = 0.8 are shown in Figure S3. It can be seen from the figure that the Mg, Nb, and O elements distribute uniformly, and however, the distributions of the Sn element for the samples of x = 0.1 and x = 0.2 seem to be nonuniform as there are numerous vacancies in the spectroscopies of the surface for the samples.…”

Experimental and Simulation Studies of Temperature Effect on Thermophysical Properties of Graphene-Based Polylactic Acid

“…It is important to point out that the as-received filler is already in a stacked form, which is preserved during the extrusion process. Moreover, this arrangement is also favored by the layer-by-layer sample production through 3D printing technology based on fused deposition modeling (FDM), as already observed with other layer-by-layer growth mechanisms and nanoparticles [ 43 ].…”