Enhanced activity and interfacial durability study of ultra low Pt based electrocatalysts prepared by ion beam assisted deposition (IBAD) method

Ultra low loading noble metal (0.04-0.12 mg(Pt)/cm(2)) based electrodes were obtained by direct metallization of non-catalyzed gas diffusion layers via dual ion beam assisted deposition (IBAD) method. Fuel cell performance results reported earlier indicate significant improvements in terms of mass specific power density of 0.297 g(Pt)/kW with 250 angstrom thick IBAD deposit (0.04 mg(Pt)/cm(2) for a total MEA loading of 0.08 mg(Pt)/cm(2)) at 0.65 V in contrast to the state of the art power density of 1.18 g(Pt)/kW using 1 mg(Pt(MEA))/cm(2) at 0.65 V. In this article we report the peroxide radical initiated attack of the membrane electrode assembly utilizing IBAD electrodes in comparison to commercially available E-TEK (now BASF Fuel Cell GmbH) electrodes and find the pathway of membrane degradation as well. A novel segmented fuel cell is used for this purpose to relate membrane degradation to peroxide generation at the electrocle/electrolyte interface by means of systematic pre and post analyses of the membrane are presented. Also, we present the results of in situ X-ray absorption spectroscopy (XAS) experiments to elucidate the structure/property relationships of these electrodes that lead to superior performance in terms of gravimetric power density obtained during fuel cell operation. (C) 2009 Published by Elsevier Ltd.