Electrocatalytic activity of Au nanoparticles onto TiO2 nanotubular layers in oxygen electroreduction reaction: size and support effects

Electrocatalytic activity of both bare high-ordered TiO2 nanotubes (TNTs) and gold nanoparticles (Au NPs) loaded TNTs toward oxygen reduction reaction (ORR) has been examined by cyclic voltammetry (CV). Cyclic voltammograms for Au NPs-TNT electrodes are characterized by an additional wave observed at less negative potentials which is responsible for oxygen electroreduction on the surface of gold NPs. The overpotential for O-2 reduction on the Au surface grows with increasing the temperature of TNT annealing and the Au NPs size. The nature of the effects observed was explained by peculiarities of the electron transport through Schottky barrier formed at the Au NPs - TiO2 interface. The width of the Schottky barrier, determined by semiconductor doping level and Au NPs size, plays a key role in the mechanism of electron transport through the space charge region. (C) 2016 Elsevier Ltd. All rights reserved