PdNi alloy nanoparticles assembled on cobalt ferrite-carbon black composite as a fuel cell catalyst

Abstract

PdNi alloy nanoparticles (NPs) were synthesized and then readily assembled on the composite of cobalt ferrite NPs with Vulcan XC-72 carbon (CoFe2O4-VC). The electrocatalyst performance of the yielded PdNi/CoFe2O4-VC composite was tested in borohydride fuel cell reactions in alkaline media. The structure/morphology of colloidal CoFe2O4 and PdNi alloy NPs along with the yielded CoFe2O4-VC composite and PdNi/CoFe2O4-VC electrocatalyst were examined by TEM, powder XRD and ICP-MS. Both monodisperse CoFe2O4 and PdNi alloy NPs with 11 and 4 nm average size, respectively, were discernible over the VC support material by the TEM images of the electrocatalyst. The loading ratio of CoFe2O4 and PdNi alloy NPs in the composite was found to be 16.1 wt% and 2.7 wt%, respectively, as determined by ICP-MS. The performance of PdNi/CoFe2O4-VC as a novel electrocatalyst for oxygen reduction (ORR) and borohydride oxidation (BOR) reactions in alkaline media was studied by voltammetric techniques using a rotating disk electrode. ORR and BOR parameters such as number of exchanged electrons and kinetic current density were calculated. The results revealed that PdNi/CoFe2O4-VC electrocatalyst was highly efficient for both ORR and BOR with exchange of 3.2 and 6.6 electrons, respectively.