Gold-Cobalt Deposited on Titania Nanotubes as Anode Catalyst for Direct Borohydride Fuel Cells

Abstract

In the present work gold-cobalt catalysts deposited on titania nanotubes surface (denoted as Au(Co)/TiO2-NTs) were investigated as anode material in direct borohydride fuel cells (DBFCs). The catalysts were prepared by a simple and cost-effective galvanic displacement technique [1]. At first, the sub-layer of Co was deposited on the titania nanotubes surface via electroless deposition. The gold crystallites were then deposited on the Co/TiO2-NTs electrodes by their immersion into gold(III)-containing solution for different time periods. It has been determined that the Au loadings were in the range from 10 to 60 µg cm–2 in the Au(Co)/TiO2-NTs catalysts. Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDXS) were used to characterize the surface morphology and composition of the samples, respectively. The activity of the Au(Co)/TiO2-NTs catalysts for borohydride oxidation reaction (BOR) was evaluated by cyclic voltammetry and chronoamperometry measurements. The performance of a DBFC operating with 1 M NaBH4 + 4 M NaOH as fuel and 5 M H2O2 + 1.5 M HCl as oxidant, while employing Pt as the cathode catalyst and Au(Co)/TiO2-NTs with different Au loadings as the anode catalyst were investigated. Peak power densities up to 122 mW cm-2 were attained at 25 ºC. It was found that the highest specific peak power density of 9.6 kW g–1 Au was obtained when employing Au(Co)/TiO2-NTs with the Au loading of 10 µg cm–2as the anode catalyst.