Electrochemical reduction on nanostructured TiO2 for enhanced photoelectrocatalytic oxidation

The influence of an electrochemical treatment method was investigated for two different TiO2 nano-structured 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. (C) 2019 Elsevier Ltd. All rights reserved.