Adjusting the energy band of Cu2O by changing the deposition conditions and its effect on photoelectrochemistry performance of Cu2O/TiO2 heterojunction

The band structure of heterojunction plays an important role in the performance of actual application and can be adjusted by the change of preparation condition. Herein, Cu 2 O nanofilms with different band structures were prepared via electrodeposition method by modifying the solution environment. With the value of pH increased from 7 to 12, the conductivity of the Cu₂O nanofilms shifted from n-type to p-type. Combined the obtained Cu 2 O film with TiO 2 nanoarray, the Cu 2 O/TiO 2 heterojunction were prepared. The photoelectrochemical performance of the Cu 2 O/TiO 2 heterojunction was affected by the interfacial band structure. The T7 sample has higher photocurrent (450 μA) caused by the unique S-scheme band structure, the T11 sample with a p-n junction structure takes second place (225 μA). The n-n type II heterojunction has the lowest photocurrent (20 μA). The Fermi level of Cu 2 O nanofilm was affected by the type of defects, such as oxygen and copper vacancies, leading to changes of band structure at the interface between Cu 2 O and TiO 2 . The obtained result further illustrates the importance of energy band engineering, and provides route and sight for the development and application of Cu 2 O/TiO 2 heterojunction.