Shape Control Beyond the Seeds in Gold Nanoparticles

Abstract

In typical seed-mediated syntheses of metal nanocrystals, the shape of the nanocrystal is determined largely by the seed nucleation environment and subsequent growth environment (where “environment” refers to the chemical environment, including the surfactant and additives). In this approach, crystallinity is typically determined by the seeds, and surfaces are controlled by the environment(s). However, surface energies, and crystallinity, are both influenced by the choice of environment(s). This limits the permutations of crystallinity and surface facets that can be mixed and matched to generate new nanocrystal morphologies. Here, we control post-seed growth to deliberately incorporate twin planes during the growth stage to deliver new final morphologies, including twinned cubes and bipyramids from single-crystal seeds. The nature and number of twin planes, together with surfactant control of facet growth, define the final nanoparticle morphology. Moreover, by breaking symmetry, the twin planes introduce new facet orientations. This additional mechanism opens new routes for the synthesis of different morphologies and facet orientations.

Copper assisted symmetry and size control of gold nanobars

“…5(A)). The latter also leads to the nanoparticle morphologies of cuboids, RBPs and rods, 40 however the yield of nanocuboids based on the analysis of 260 particles is 48%, lower than with Cu 2+ (Fig. 5(B) and Fig.…”

“…S12, ESI†), consistent with the size reported in the literature. 6,40 In stark contrast, the Cu 2+ -assisted gold nanobars have a transition size of 17–19 nm (Fig. 3, and Fig.…”

“…5(C) shows that the edge length of the nanocuboids in the absence of Cu 2+ is around 50 nm, almost twice that of Cu 2+ -assisted gold nanobars, and furthermore, the nanocuboids incorporate lamellar twin planes. 40 The cuboid edge length was measured for the two syntheses and plotted in Fig. 5(C).…”

Seed free synthesis of polyethylene glycol stabilized gold nanoprisms exploiting manganese metal at low pH

“…The interplanar distance for this packing has been found to be 0.14 nm, which arises due to (0 22) planes. 50 SAED patterns conrm the presence of the twinned structure. 51,52 In the presence of 1.2 equivalents of PEG, the number of nanoprisms has signicantly dropped down and small nanoclusters have been observed around the corner of the nanoprisms (Fig.…”

Hydrogels allow the precise growth tracking of plasmonic gold nanoparticles for mercury analysis

“…Gold nanoparticles (NPs) are formed by the accumulation of gold atoms with diameters of 5-100 nm and have unique and intriguing physical and chemical properties such as local surface plasmon resonance (LSPR) effects, surface-enhanced Raman scattering, and chemical catalysis. [1][2][3][4][5] When gold NPs are irradiated by light, the photon energy is absorbed due to the LSPR effect. The wavelength peak and absorbance of LSPR are related to the composition, sizes, and shapes of nanoplasmonics as well as the distance between individual NPs.…”