Platinum-Based Nanowire Networks with Enhanced Oxygen-Reduction Activity

Pt-Al and Pt-Y-Al thin-film electrodes on yttria-stabilized zirconia electrolytes were prepared by dealloying of cosputtered Pt-Al or Pt-Y-Al films. The selective dissolution of Al from the Pt-alloy compound causes the formation of a highly porous nanowire network with a mean branch thickness below 25 nm and a pore intercept length below 35 nm. The oxygen-reduction capability of the resulting electrodes is analyzed in a micro-solid-oxide fuel-cell setup at elevated temperatures (598–873 K). Here, we demonstrate that these nanoporous thin films excel “state-of-the-art” fuel-cell electrodes in terms of catalytic activity and thermal stability. The nanoporous Pt electrodes exhibit exchange-current densities that are up to 13 times higher than conventional Pt electrodes, measured at 648 K. It is shown that the enhanced intrinsic electrocatalytic activity of these Pt electrodes is achieved by the addition of yttrium as a ternary constituent, which allows for an engineering of the material’s band structure.