Electrochemical oxidation of sodium borohydride on carbon supported Pt-Zn nanoparticle bimetallic catalyst and its implications to direct borohydride-hydrogen peroxide fuel cell

Abstract

Carbon supported Pt-Zn bimetallic nanoparticle electrocatalysts (Pt-Zn/C) are facilely prepared by a modified NaBH4 reduction method in aqueous solution at room temperature and investigated as alternative anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared nanospherical electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and fuel cell test. Based on results of TEM and XRD, the Pt-Zn nanoparticles show average particle size of approximately 2.5nm on the carbon surface. The fundamental electrochemical results show that the Pt-Zn/C catalysts exhibit much higher catalytic activity and stability for the direct oxidation of BH4− than Pt/C catalyst since Pt atoms are partly substituted by Zn atoms in Pt-Zn catalyst. Among various Pt-Zn catalysts with different compositions, the Pt67Zn33/C catalyst presents the highest catalytic activity for BH4− electrooxidation. The DBHFC using Pt67Zn33/C as anode catalyst and Pt/C as cathode catalyst obtains the maximum power density as high as 79.9mWcm−2 at 79.5mAcm−2 and 25°C.