Cu-Cu2O-TiO2 nanojunction systems with an unusual electron-hole transportation pathway and enhanced photocatalytic properties.

Multicomponent Cu-Cu2O-TiO2 nanojunction systems were successfully synthesized by a mild chemical process, and their structure and composition were thoroughly analyzed by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The as-prepared Cu-Cu2O-TiO2 (3 and 9 h) nanojunctions demonstrated higher photocatalytic activities under UV/Vis light irradiation in the process of the degradation of organic compounds than those of the Cu-Cu2O, Cu-TiO2, and Cu2O-TiO2 starting materials. Moreover, time-resolved photoluminescence spectra demonstrated that the quenching times of electrons and holes in Cu-Cu2O-TiO2 (3 h) is higher than that of Cu-Cu2O-TiO2 (9 h); this leads to a better photocatalytic performance of Cu-Cu2O-TiO2 (3 h). The improvement in photodegradation activity and electron-hole separation of Cu-Cu2O-TiO2 (3 h) can be ascribed to the rational coupling of components and dimensional control. Meanwhile, an unusual electron-hole transmission pathway for photocatalytic reactions over Cu-Cu2O-TiO2 nanojunctions was also identified.