Size Control and Growth Process of Alkylamine-Stabilized Platinum Nanocrystals:  A Comparison between the Phase Transfer and Reverse Micelles Methods

Abstract

Alkylamine-stabilized platinum nanoparticles are synthesized either by the phase-transfer method or in reverse micelles. The phase-transfer method produces nanocrystals that are quite spherical whereas the synthesis in reverse micelles generates a large number of wormlike structures. An alkylamine is used as a stabilizing agent to prevent nanoparticle coalescence, and it is shown that there is an inverse relationship between the alkylamine chain length and the platinum nanoparticle diameter. By comparing alkylamine and alkylthiol analogues, it is found that the integrity of the different crystallites depends on the strength of the interaction between the stabilizing agent and the platinum nanocrystals. The results obtained and the comparison made between the two synthesis methods improve the understanding of the growth mechanisms of platinum nanocrystals in disperse media.

On the influence of Pt particle size on the PEMFC cathode performance

“…As expected, the mean nanoparticle diameter varied dependant on the chain length of the employed alkyamine. The Pt-C 12 NH 2 nanoparticle mean diameter was 1.6 ± 0.6 nm (denoted PTM-1) whereas the size of the Pt-C 8 NH 2 nanoparticles (denoted PTM-2) was 2.4 ± 0.3 nm consistent with previously reported results [10], see Table 2. The extended growth of Pt-C 8 NH 2 nanoparticles (see Section 2) gave a mean size of 2.6 ± 0.5 nm (denoted PTM-3) in diameter.…”

“…In the case of nanoparticles of noble metals, such as Ag, Au, Pt or Pd, alkylthiols (C n SH) [4,[6][7][8] and alkylamines (C n NH 2 ) [9,10] are common stabilizing agents, but also other organic compounds such as alkyl isocyanide can be used [11]. A benefit of using alkylamines in the PTM, as shown in a recent study, is that the diameter of Pt nanoparticles is influenced by the chain length of the surrounding alkylamine [10].…”

Evaluation of the intrinsic kinetic activity of nanoparticle ensembles under steady-state conditions

“…The particle sizes measured by TEM are larger than the aqueous core of the reverse micelles predicted by Eq. (2) and this discrepancy has been attributed to the dynamic nature of the reverse micelle preparation [81,91,101]. For example, the radius for the W2 NPs, as shown in the histogram, was 1.4 ± 0.1 nm.…”

Preparation of size-tunable, highly monodisperse PVP-protected Pt-nanoparticles by seed-mediated growth

“…Therefore, a series of differently sized particles of consummate monodispersity are necessary to elucidate size and shape effects in catalysis. Despite a large choice of synthetic methods published in the literature which produce platinum metal nanoparticles of decent monodispersity and relatively uniform shape, most common techniques are either limited to a single particle size 10 or a narrow size-range 11 for which the growth conditions have been optimized. Even nowadays, a significant fraction of newly published preparation techniques produce polydisperse samples 12 .…”