Paper PS2-ThA11
Plasma Deposited Films Containing Platinum Nanoclusters as Catalysts for Fuel Cells

Thursday, October 23, 2008, 5:20 pm, Room 306

Today, the development of fuel cells is a promising solution to the “energy crisis” and the necessity to provide “clean energy” with virtually zero emission. Fuel cells offer the possibility of abundant energy with negligible emission and high efficiency for converting chemical energy into electricity and heat; however, one of the major disadvantage is their high production cost. Extensive studies are currently addressed to the development of new materials with the aim of improving fuel cell efficiencies and decrease production costs. As far as the catalyst is concerned, nanocomposites films consisting of metal nanoparticles embedded in polymeric matrix are very attractive materials because they allow to decrease the overall amount of Pt while providing high surface area. In literature various approaches have been used to incorporate metal nanoparticles into polymers. In this contribution a one-step plasma deposition process is described to obtain an uniform dispersion of small platinum nanoclusters throughout a thin hydrocarbon matrix. These composite films have been deposited by simultaneous plasma-enhanced chemical vapour deposition (PECVD) of ethylene (C₂H₄) and argon (Ar) gas mixtures and RF sputtering of a platinum target. Characterization of platinum-containing plasma-polymerized ethylene films has been realized using X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infra-Red spectroscopy (FT-IR), UV-Vis spectroscopy, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Optical Emission Spectroscopy (OES) has been used to correlate the chemical composition of the plasma with the amount of metal embedded in the deposited film. The electrochemical active area of the samples was determined from ex-situ cyclic voltammetry analyses. A comprehensive study on the effect of different plasma parameters (RF power, deposition time, flow rate of gasses) on the chemical composition and structure of the film will be presented. Results show that the platinum content in the coating can be finely controlled by changing the RF power and the monomer flow rate. In particular TEM images confirm that platinum aggregates in crystalline nanoclusters in distributed uniformly in the material. Furthermore the porosity due to the columnar film growth, together with the nanodispersion of the metal clusters, can be advantageously used for catalytic applications.