Designed synthesis of anatase–TiO2 (B) biphase nanowire/ZnO nanoparticle heterojunction for enhanced photocatalysis

Abstract

A high performance photocatalyst based on a heterostructure using ZnO nanoparticles (NPs) decorating mesoporous anatase–TiO₂ (B) biphase TiO₂ nanowires (NWs) was synthesized by a facile water bath reflux method. The morphology, structure, and optical properties of the prepared hybrid photocatalyst were well characterized. The results showed that the mesoporous biphase TiO₂ NWs consisted of TiO₂ (B) and anatase phases. When ZnO NPs were loaded on the surface of biphase TiO₂ NWs, a heterojunction was formed between TiO₂ NWs and ZnO NPs that could favor the separation of photogenerated electron–hole pairs. The TiO₂–ZnO heterojunction exhibited remarkably enhanced photocatalytic activity and excellent stability for both dye degradation and H₂ evolution compared with TiO₂ NWs. The heterojunction with a 20 wt% ZnO content exhibited the highest photocatalytic activity and the reaction rate constant was about 4.2 and 1.3 times higher than that of TiO₂ NWs for dye degradation and H₂ evolution, respectively. The main active species were found to be O₂˙⁻ and ˙OH by the electron paramagnetic resonance technique. This work may open a promising avenue in producing highly efficient heterojunction photocatalysts with special structures for large-scale environmental and energy applications.