Design Of Cu₂O Quantum Dots And TiO₂ Photonic Crystal Composite Catalyst And Its Photocatalytic Performance

The photocatalysis of semiconductor, such as Ti O2, has been considered as one of the most promising technology for environmental pollution control. However, the application of Ti O2 is limited by the narrow light response region and low quantum efficiency. Herein, the Cu2 O quantum dots(QDs) were integrated with Ti O2 photonic crystal(PC). The compiste catalyst(Cu2O QDs/Ti O2 PC) exhibited extended light harvesting due to the Cu2 O visible light absortion which was intensified by the band gap scattering effect and slow light effect of Ti O2 PC. The p-n heterojunction between p-Cu2 O and n-Ti O2 can also promote the light carrier transfer and thus improve the light quantum efficiency of catalyst. In addition, the macroporous structure of Ti O2 PC was help for the mass transfer of pollutants and dissolved oxygen, increasing the photocatalytic efficiency. The specific research results were shown as following:The composite semiconductor photocatalyst Cu2 O QDs/Ti O2 PC was prepared via the liquid phase deposition and hydrothermal reduction method. The average pore size of the face-centered cubic structure was around 234 nm, and the thickness was about 2 μm. Size of 8-10 nm Cu2 O QDs quantum dot evenly deposited on the surface of the 3D PC structure. The position of Ti O2 PC photon forbidden band width and center position was tuned to match the the optical absorption of Cu2 O quantum dots by changing the template microspheres size.During the photocatalytic degradation of Rhodamine B(Rh B), Bisphenol A(BPA) and p-nitrophenol(p-NP) under the simulated sunlight irradiation, the kinetic constants of Cu2 O QDs/Ti O2 PC were 2.7, 5.5 and 3.2 fold higher than that of Cu2 O QDs/Ti O2 NC, respectively. The superoxide radicals was the main reactive oxygen species during the photocatalytic degradation of p-NP.The above results illuminated that the wide band gap semiconductor Ti O2 deposited on Cu2 O QDs could expand the light absorption range, and the separation of photogenerated electron-hole pairs could also be intensified by the p-n heterojunction. The photonic crystal of Ti O2 could enhance the quantum effiency of photocatalytic. These studies provide feasible method for optimization of photocatalyst and was hoped to develop the photonic crystal theory and heterojunction theory in the field of environmental pollution controlling.