Oxygen reduction on potentiodynamically formed Pd/TiO <inf>2</inf> composite electrodes

Abstract

By multiple potentiodynamic polarization of polished titanium surface in an aqueous PdCl 2 solution, a thin composite Pd/TiO 2 layer was formed, consisting of Pd submicron particles grown through a nanometer-thin surface TiO 2 layer. The real surface area of Pd was determined by cyclic voltammetry in nitrogen purged 0.1 mol dm -3 HClO 4. The oxygen reduction reaction on the Pd/TiO 2 layer in 0.1 mol dm -3 KOH and 0.1 mol dm -3 HClO 4 solutions has been studied using rotating disc electrode (RDE) voltammetry. Comparing to the best palladium or palladium based catalysts published thus far, the Pd/TiO 2 composite yielded similar or higher (in acidic solution) or discernible higher (in alkaline solution) rate of oxygen reduction. This was found to be mostly due to the high surface area of Pd particles, but, to some extent, due to the influence of TiO 2 support itself. © 2012 Elsevier Ltd.