Quantitative Analysis of the Role Played by Poly(vinylpyrrolidone) in Seed-Mediated Growth of Ag Nanocrystals

Abstract

This article presents a quantitative analysis of the role played by poly(vinyl pyrrolidone) (PVP) in seed-mediated growth of Ag nanocrystals. Starting from Ag nanocubes encased by {100} facets as the seeds, the resultant nanocrystals could take different shapes depending on the concentration of PVP in the solution. If the concentration was above a critical value, the seeds simply grew into larger cubes still enclosed by {100} facets. When the concentration fell below a critical value, the seeds would evolve into cuboctahedrons enclosed by a mix of {100} and {111} facets and eventually octahedrons completely covered by {111} facets. We derived the coverage density of PVP on Ag(100) surface by combining the results from two measurements: i) cubic seeds were followed to grow at a fixed initial concentration of PVP to find out when {111} facets started to appear on the surface; and ii) cubic seeds were allowed to grow at reduced initial concentrations of PVP to see at which concentration {111} facets started to appear from the very beginning. We could calculate the coverage density of PVP from the differences in PVP concentration and the total surface area of Ag nanocubes between these two samples. The coverage density was found to be 140 and 30 repeating units per nm2 for PVP of 55,000 and 10,000 g/mol in molecular weight, respectively, for cubic seeds of 40 nm in edge length. These values dropped slightly to 100 and 20 repeating units per nm2, respectively, when 100-nm Ag cubes were used as the seeds.

Observation of Metal Nanoparticles for Acoustic Manipulation

“…As shown by the transmission electron microscopy (TEM) images in Figure 1 a, highly monodisperse silver nanocubes with typical structures of about 50, 100, and 150 nm in edge length were synthesized, namely NP50‐0, NP100‐0, and NP150‐0, respectively. Optical characterization of the samples by UV–vis spectroscopy (Figure 1d) showed that the major localized surface plasmon resonance (LSPR) absorption band is redshifted from 450 to 590 nm with the increase of particle size, in agreement with those previously reports 38. To get the hollow nanostructures with various porosities, as‐prepared silver nanocubes were used as sacrificial templates and reacted with increasing amounts of chloroauric acid via the galvanic replacement reaction (Figure 1c).…”

“…As one of the most representative and well‐established metal nanomaterials, silver nanocubes were chosen and synthesized according to the previous reports with some modifications 36, 37, 38. As shown by the transmission electron microscopy (TEM) images in Figure 1 a, highly monodisperse silver nanocubes with typical structures of about 50, 100, and 150 nm in edge length were synthesized, namely NP50‐0, NP100‐0, and NP150‐0, respectively.…”

“…Nanoparticles Preparation : Silver solid nanocubes with three different sizes were prepared, according to the previous reports with some modifications 36, 37, 38. Briefly, 20 mL of ethylene glycol (EG, Aladdin) was added into a 100 mL glass vial and heated under magnetic stirring in an oil bath at 150 °C for 1 h. Then, 240 µL of NaSH (Aladdin, 3 × 10 −3 m in EG) was quickly injected into the heated solution.…”

Facet‐Controlled Synthetic Strategy of Cu2O‐Based Crystals for Catalysis and Sensing

“…To date, CAs have played an important role on shape‐controlled synthesis of NCs,137, 138, 139, 140, 141, 142 and there are many successful examples in preparing Cu 2 O NCs 7, 8, 75, 107, 122, 125, 143. We will introduce some classic synthetic routes of Cu 2 O NCs enclosed by low‐index facets.…”

Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires

“…Here, organic ligands such as myristic acid or alkanethiol are bound at nanoparticle surfaces to prevent Ag particle aggregation, generally producing very monodispersive spherical particles 6,7 . Capping agents such as poly(vinyl pyrrolidone) may be used to modify seed crystal surface to enable growth of oriented Ag nanorods and nanowires 8 . Poly(vinyl pyrrolidone is understood to preferentially interact with specific nanocrystal surfaces such as {100} to inhibit growth of that orientation, compared with other crystal faces, enabling in oriented one-to two-dimensional (1-2D) Ag nanostructures.…”