Platinum–Dendrimer Nanocomposite Films on Gold Surfaces for Electrocatalysis

Abstract

In this communication, we report a strategy for the preparation of Pt nanoparticles encapsulated in Generation 4.5 (Polyamido amine) PAMAM dendrimer and subsequent chemical linking of the nanocomposite to the gold electrode through a self assembled cystamine monolayer. The modification resulted in the formation of a robust electrochemically active thin film with very high surface area, reflected by the enhanced hydrogen adsorption coverage. Interestingly, TEM images revealed selfassembly of Pt nanoparticles and the SAED (Selected Area Electron Diffraction) patterns showed the presence of Pt single crystals (111). The Pt-dendrimer nanocomposite film obtained using the novel modification procedure exhibited high electrocatalytic activity for the oxidation of organic fuels like methanol, ethanol and ethylene glycol. The film did not suffer from degradation even after repeated use in solution-phase voltammetry. It is however observed that the intermediate SAM layer and the bulky PAMAM dendrimer (generation 4.5) have slowed down the electron transfer kinetics which is reflected by a relatively high overpotential for methanol oxidation. Nevertheless this shortcoming is more than compensated by the existence of Pt(111) planes, which alleviate CO poisoning.

Molecular dynamics simulations of polyaminoamide (PAMAM) dendrimer aggregates: molecular shape, hydrogen bonds and local dynamics

“…[9][10][11][12][13][14][15][16] Indeed, their chemical composition with several internal amide groups and external amine terminal groups make them suitable for biomedical applications 17 as well as for ''bottom up'' materials for nanotechnology. 18,19 Recently experimental studies have also investigated their ability to self assemble on surfaces or in solutions. 20 For many of the applications cited above, the understanding of the molecular structure of dendrimers in bulk represents one of the most important prerequisites for their controlled design.…”

Coordination and Reduction Processes in the Synthesis of Dendrimer-Encapsulated Pt Nanoparticles

“…Following the successful synthesis of dendrimer-encapsulated Cu nanoparticles by Crooks et al and Balogh and Tomalia, several other research groups attempted to synthesize various types of nanoparticles. Some of these include Au, 8-21 Ag, 9,22 Cu, 7,23 Pd, 15,19,20,[23][24][25][26][27][28][29][30][31][32][33][34] Pt, 9,24,29,32,[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Fe, 54 Ni, 55 Ru, 51,56,57 and Ir 58 nanoparticles, as well as involving the *Corresponding author. E-mail: miyahara@cheme.kyoto-u.ac.jp.…”

“…Some of these include Au,− Ag, , Cu, , Pd, ,,,− Pt, ,,,,− Fe, Ni, Ru, ,, and Ir nanoparticles, as well as involving the coordination process. For example, the maximum number bimetallic− and semiconductor ,− nanoparticles, which have good magnetic properties and show photoluminescence and unique catalytic activities . In addition, it is demonstrated that different types of dendrimers such as a functionalized poly(propyleneimine) dendrimer with a smaller diameter , and a phenylazomethine dendrimer with more rigid structure than those of PAMAM yield dendrimer-encapsulated nanoparticles, although a PAMAM dendrimer has been so far most widely used.…”

“…The surface charge of G4.5-COO − enables better handling of the nanoparticles because of electrostatic interactions, which can lead to the formation of ordered structures via controlled nanoparticle deposition. However, in previous studies, it has been found that the nanoparticles obtained using G4.5-COO − dendrimers were larger than those obtained using G4-OH dendrimers. ,, The effect of the surface groups of the dendrimer on the nanoparticle size is thus worth discussing. In the present study, we systematically examine the effects of pH, temperature, coordination time, and surface functional groups of dendrimers on the coordination process and the resultant Pt nanoparticles.…”

PAMAM Dendrimers as Anchors for the Preparation of Electrocatalytically Active Ultrathin Metallic Films

“…[1][2][3][4] Their special architecture arises due to their extraordinary symmetry, high branching, and maximized terminal functionality density. [8] Many researchers have prepared dendrimer-metal nanocomposites, which are based on metal complexation by the tertiary amine groups present inside the dendrimer followed by chemical reduction with borohydride. [5][6][7] Incorporation of nanoparticles onto electrode surfaces to realize electrocatalysis has always been a fascinating and challenging study.…”