Hierarchical Heterostructure of ZnO@TiO₂ Hollow Spheres for Highly Efficient Photocatalytic Hydrogen Evolution

The rational design and preparation of hierarchical nanoarchitectures are critical for enhanced photocatalytic hydrogen evolution reaction (HER). Herein, well-integrated hollow ZnO@TiO₂ heterojunctions were obtained by a simple hydrothermal method. This unique hierarchical heterostructure not only caused multiple reflections which enhances the light absorption but also improved the lifetime and transfer of photogenerated charge carriers due to the potential difference generated on the ZnO-TiO₂ interface. As a result, compared to bare ZnO and TiO₂, the ZnO@TiO₂ composite photocatalyst exhibited higher hydrogen production rated up to 0.152 mmol h^-1 g^-1 under simulated solar light. In addition, highly repeated photostability was also observed on the ZnO@TiO₂ composite photocatalyst even after a continuous test for 30 h. It is expected that this low-cost, nontoxic, and readily available ZnO@TiO₂ catalyst could exhibit promising potential in photocatalytic H₂ to meet the future fuel needs.