Cu oxide quantum dots loaded TiO2 nanosheet photocatalyst for highly efficient and robust hydrogen generation

To simultaneously enhance both the hydrogen generation activity and long term stability of a TiO2 based photocatalyst using Cu species as co-catalyst is a great challenge. In this work, highly reactive TiO2 nanosheets with {0 0 1} facets were prepared by a hydrothermal method, and then Cu oxides quantum dot was loaded on the nanosheets by an impregnation method. Comprehensive analysis demonstrates that the Cu species change from CuO to Cu2O and partially to Cu during photocatalysis, and this process is reversed during oxidation. The exposed TiO2 (0 0 1) planes provide a platform for a strong interaction between the Cu oxide and TiO2 nanosheets, enabling the firmly anchor and charge transfer between the Cu oxide and TiO2. The optimized composite photocatalyst shows a high efficiency and robust, long term stability for H2 evolution. With simple O2 regeneration, the H2 generation rate maintains to 98% after irradiation for 30 h. It is expected that Cu2O is sandwiched between TiO2 and CuO, and the composite configuration changes to TiO2/Cu2O/Cu after long term irradiation. The energy band alignment of the double heterojunction provides the effective charge separation and maintains the structural stability during the photocatalysis.