SnO^sub 2^-C supported PdNi nanoparticles for oxygen reduction and borohydride oxidation

Palladium-nickel nanoparticles supported on different tin oxide-carbon composites, namely PdNi/(SnO2-KB600), PdNi/(SnO2-KB300) and PdNi/(SnO2-graphene), as well as on Vulcan XC-72 (PdNi/Vulcan), are prepared and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The electrocatalytic activity of each material for the oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) is studied in alkaline media by voltammetric techniques using rotating disk electrode (RDE) and rotating ring disk electrode (RRDE). ORR and BOR parameters, such as number of exchanged electrons, kinetic current density, Tafel slope and activation energy, are calculated. ORR n values at 0.2 V are close to 4 for PdNi/(SnO2-KB600) and PdNi/Vulcan, and close to 2 for PdNi/(SnO2-KB300) and PdNi/(SnO2-graphene). BOR n values range from 1.9 for PdNi/(SnO2-graphene) to 3.4 for PdNi/(SnO2-KB300). The materials stability is examined by chronoamperometry. The obtained results show that PdNi nanoparticles anchored on SnO2-KB600 support are good electrocatalyst candidates for both ORR and BOR in alkaline media.