Amorphous Ni59Nb40PtxM1-x (M = Ru, Sn) electrocatalysts for oxygen reduction reaction

The oxygen reduction reaction, ORR, on amorphous Ni59Nb40Pt1, Ni59Nb40Pt0.6Ru0.4 and Ni59Nb40Pt0.6Sn0.4 electrocatalysts was analyzed by electrochemical techniques such as cyclic voltammetry, CV; rotating disk, RDE, and ring-disk electrodes, RRDE, in a 0.5 M H2SO4 solution. The reduced amount of platinum and the incorporation of transition metals in the amorphous catalysts were found to have significant effect on the kinetic parameters of the cathodic reaction. The kinetics study (RRDE) performed on the amorphous catalysts showed a high activity towards the ORR, preferentially proceeding via multi-electron (4e(-)) charge transfer pathway toward water formation, with less than 2.8% H2O2 in the region of PEMFC applications. The performance on Ni59Nb40Pt1 was different, which may be related to changes in the electrode surface enrichment of one or two of the amorphous alloy constituents. The performance towards the cathodic reaction allows to envisage that incorporation of small amounts of Pt in the catalyst, may lead to the fabrication of good amorphous electrocatalytic materials with possible applications as cathode electrodes in polymer electrolyte fuel cells. (C) 2008 Elsevier B.V. All rights reserved.