Electrodeposited Cu2O on the {101} facets of TiO2 nanosheet arrays and their enhanced photoelectrochemical performance

A novel Cu2O/{101}TiO2 nanosheet (Cu2O/{101}TNS) array film was prepared by the electrodeposition of Cu2O on the {101} facets of anatase nanosheet arrays by varying electrodeposition potential. The crystal structure, morphology, elemental chemical states, optical properties, photoelectrochemical properties, and stability of Cu2O/{101}TNS array films were investigated in detail. For TNS, due to different band structures and band edge positions between {001} and {101} facets, Cu2O/{101} facets of TiO2 have higher band offset value which supply a larger driving force to increase the transport efficiency of carriers. Besides, owing to the directional flow of photo-generated electrons from {001} to {101} facets, the electrodeposition of Cu2O on the {101} facets of TNS will shorten the route length that the electrons must travel, thus reduce recombination of photo-generated electron-hole pairs. In addition, as the applied negative potential is high enough, a part of Cu+ is reduced to Cu, which is beneficial for the photoexcited electrons transfer from CB of Cu2O to that of TiO2. The enhanced photoelectrochemical properties of Cu2O/{101}TNS array films can be attributed to the cocontributions of different band edge positions between {001} and {101} facets, Cu2O-Cu-TiO2 ternary components and vertically aligned single-crystal TiO2 nanosheet structure.