Electrochemical reduction on nanostructured TiO2 for enhanced photoelectrocatalytic oxidation

Abstract

The influence of an electrochemical treatment method was investigated for two different TiO2 nanostructured materials, anatase nanotubes (TNT) and rutile nanorods (TNR). The treatment was done by performing cyclic voltammetry in acidic media. XPS measurements revealed a shift in Ti 2p peaks, suggesting the presence of Ti3+ after the partial reduction, as well as an increased peak associated to a higher hydroxylation degree of the surface. The treatment leads to an increase in the maximum photocurrent density, confirmed from linear sweep voltammograms and photon-to-electron conversion efficiencies (IPCE). The treatment is assumed to modify the charge carrier separation kinetics by inducing partial reduction of the TiO2. A markedly increased of two and three-fold in the IPCE was obtained for the reduced TNT and TNR, respectively, up to a maximum of 77% for TNR. This electrochemical treatment represents a facile and systematic approach to modify TiO2 nanostructured electrodes to achieve enhanced photoelectrocatalytic properties, as demonstrated by the current doubling experiments with MeOH.