Electrochemical oxidation of borohydride at nano-gold-based electrodes: Application in direct borohydride fuel cells

Nano-particulate gold-based materials along with commercial gold supported over carbon were investigated as possible alternative electrocatalysts for the oxidation of borohydride in alkaline media. Cyclic voltammetry experiments conducted on these materials show very high activity for the nano-particulate materials compared to the commercial materials despite a lower loading of gold (0.8 mg cm−2 compared to 1.0 mg cm−2) and lower interface area in the nano-particulate materials. The presence of BH4− appears to have detrimental effect on the performances of the air-electrode for oxygen reduction. The current density recorded at −0.6 V versus Hg/HgO has decreased by a factor of six for silver nitrate AC65 while for MnO2 a reduction in the current density by a factor of two only was observed. The implementation of the nano-particulate gold-based materials and the air-electrodes along with a low-cost anionic membrane in QinetiQ's tubular cell design has led to power density exceeding 28 mW cm−2 obtained at ambient temperature.