The reduction of hydrogen peroxide at an Au-coated nanotubular TiO2 array

An Au-coated TiO2 nanotubular array, in the vertically aligned form, was investigated as a highly porous nanostructured electrode for the electrochemical reduction of H2O2 in an acidic sulphate electrolyte at 295 K. The TiO2 nanotubular arrays were formed via a two-stage anodising then nanosized Au particles were sputter deposited onto the surface. The following aspects were studied: (a) the shape evolution of Au particles on the nanotubular array (via surface microstructural imaging), (b) the effect of different degrees of Au loading on the nanotubular array (via voltammetric analysis) and (c) the electrochemical response of an Au–TiO2 nanotubular array compared to a plain, 2-D Au foil. The Au particles could be deposited as a thin 3-D coated layer or as nodular nanostructures on the array. The highly nanoporous structure of the Au–TiO2 electrode led to a large enhancement in the limiting current (enhancement factor up to 6.6) and charge density (enhancement factor up to 8.9) for peroxide reduction compared to a plain Au foil due to the architecture of the ordered, high surface area of the nanotubular array.