Electrodeposition of flake-like Cu 2 O on vertically aligned two-dimensional TiO 2 nanosheet array films for enhanced photoelectrochemical properties

Abstract A novel Cu 2 O/TNS composite structure of single crystal TiO 2 nanosheet (TNS) arrays decorated with flake-like Cu 2 O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu 2 O become agglomerating, and transform into dense Cu 2 O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu 2 O and n-type TiO 2 heterojunctions combined with two-dimensional TiO 2 nanosheet with exposed highly reactive {001} facets.