The characteristics and reactivity of two anodes based upon Pt supported on carbon nanotubes, with or without defects introduced by ball-milling, were studied using scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and single-cell measurements using a flow of pure H2 or a flow containing 50ppm CO. It was shown that the presence of defects influenced several properties and not only the dispersion of Pt particles. Therefore, the performances could be correlated neither with the geometrical surface area of Pt particles, nor with the electrochemical active surface area determined from cyclic voltammetry tests. The presence of defects, enhancing the number of surface functional groups on carbon nanotubes, influenced aspects such as the efficiency of three-phase boundaries and thus the transport of protons to or from the active metal particles, the resistance of electron transfer and the tolerance of the catalyst to CO poisoning. The latter was attributed to carbon functional groups in close contact with very small Pt particles, favoring the re-activation of Pt sites poisoned by CO.

The Role of Mechanically Induced Defects in Carbon Nanotubes to Modify the Properties of Electrodes for PEM Fuel Cell. G.Centi, M.Gangeri, M.Fiorello, S.Perathoner, J.Amadou, D.Bégin, M.J.Ledoux, C.Pham-Huu, M.E.Schuster, D.S.Su, J.P.Tessonnier, R.Schlögl: Catalysis Today, 2009, 147[3-4], 287-99