A gold-coated titanium oxide nanotube array for the oxidation of borohydride ions

Highly ordered titanium dioxide nanotube (≈ 100–200 nm pore diameter) arrays, were formed on a titanium foil by anodising at a cell voltage of 60 V, in two stages. The nanotube arrays were over-coated with nanoparticulate gold using physical vapour deposition (PVD) sputtering resulting in a well dispersed coating. The electrodes were used to study the oxidation of 20 × 10− 3 mol dm− 3 borohydride ions in 3 mol dm− 3 NaOH, at 298 K, by cyclic voltammetry. The gold-coated titanium oxide nanotube array electrodes provided higher electrical charge per unit mass of gold and unit area that a gold nanoparticle deposit on carbon and gold adsorbed on hydrothermally synthesised titanate nanotubes offering a reliable and low cost technique to produce a high surface area anode for a direct borohydride fuel cell.

► Highly ordered vertical aligned structures of TiO2 nanotubes with large surface area.
► TiO2 array coated with a layer of gold nanoparticulates for the oxidation of BH4−.
► The Au/TiO2 electrode produces larger electrical charge per mass of gold and area.