Search

We report here the synthesis of palladium (Pd) nanoparticles incorporated poly-(3,4)ethylenedioxythiophene (PEDOT) matrix in aqueous medium and its catalytic performance towards 4-nitrophenol reduction. This simple one-pot synthesis involving a redox reaction between 3,4-ethylenedioxythiophene and palladium chloride (PdCl2) precursor, leads to the formation of Pd nanoparticles supported on particulate PEDOT. Pd nanoparticles of size 1–9 nm were found to distribute uniformly over the PEDOT matrix. Morphology of the Pd–PEDOT nanocomposite was characterized by field emission-scanning electron microscopy and transmission electron microscopy and the crystallographic details obtained using X-ray diffraction. The chemical nature of the PEDOT support matrix was analyzed using Fourier transform-infra red (FT-IR) spectroscopy. The catalytic activity of the composite was demonstrated using a model reaction, i.e., reduction of 4-nitrophenol to 4-aminophenol. The value of the apparent rate constant, ca. 65.8 × 10−3 s−1 obtained using UV visible spectroscopy of the reduction of 4-nitrophenol at the Pd–PEDOT nanocomposite is comparable to those reported for other catalytic systems.

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 self-assembly 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.