A highly efficient TiO2@ZnO n–p–n heterojunction nanorod photocatalyst

Abstract

Shell@core-nanostructured TiO₂@ZnO n–p–n heterojunction nanorods with diameter of 30 nm were successfully fabricated via a hydrothermal method. The photodegradation rate of the TiO₂@ZnO n–p–n nanorods evaluated by photodegrading methyl orange has been demonstrated to increase three times compared to that of wurtzite hexagonal ZnO. Anatase TiO₂ and Ti₂O₃ grow along ZnO crystal lattices, which forms p-type Zn²⁺ doped Ti₂O₃ in the interface of TiO₂/ZnO and therefore numerous n–p–n heterojunctions owing to the substitution of Ti³⁺ by Zn²⁺. Under the drive of inner electric field, the photogenerated electrons are both injected to the conduction band of Zn²⁺ doped Ti₂O₃ from conduction bands of ZnO and TiO₂, which efficiently enhances the separation of photogenerated electron–hole pairs and accelerates the transport of charges. The results suggest that TiO₂@ZnO n–p–n heterojunction nanorods are very promising for enhancing the photocatalytic activity of photocatalysts.