Highly Active Photocatalyst of CuOx Modified TiO2 Arrays for Hydrogen Generation

The photocatalytic performance and the involved mechanism of copper-modified TiO2 have attracted a wide range of scientific interests in recent years. In this study, we fabricate CuOx/TiO2 photocatalysts by depositing Cu, Cu2O, and CuO on the surface area of hierarchical TiO2 arrays using magnetron sputtering method. These CuOx/TiO2 photocatalysts exhibit excellent photocatalytic performance with H-2 generation rate of 30 mmol m(-2) h(-1) for CuO/TiO2, 37 mmol m(-2) h(-1) for CU2O/TiO2, and 53 mmol m(-2) h (-1) for Cu/TiO2. We further study the composition evolution of CuOx during the photocatalytic reaction process to illustrate the actual active copper species. It is found that CuO is easily photoreduced to Cu2O and the latter can be further reduced to metallic Cu under irradiation in the solution. In the steady stage of photocatalytic reaction, the photoinduced TiO2/Cu2O/Cu three-phase system facilitates the separation of photogenerated carriers through the migration of electrons in both TiO2 and Cu2O to metallic Cu. This study demonstrates that the effective copper-based cocatalyst in various CuOx/TiO2 systems exists in the metallic form.