Photocatalytic study of a novel crystal facets sensitive heterojunction between Sb8O11Cl2 and anatase TiO2 with different exposed facets

In this work, Sb8O11Cl2 was composited with TiO2 with different exposed facets to construct heterostructure and related photocatalytic activity was studied. The results reveal that this TiO2/Sb8O11Cl2 heterostructure is crystal facets sensitive. When Sb8O11Cl2 was loaded on the {001} facets of TiO2 nanosheets with coexposed {101} and {001} facets, the photo-induced carriers' separation efficiency is enhanced and related photocatalytic activity is improved with a ratio of 74% under optimal composited ratio. However, the carriers' separation efficiency and related photocatalytic activity almost had no variation when Sb8O11Cl2 was composited with P25 which is mainly constituted by anatase TiO2 with exposed {101} facets. Pure anatase TiO2 nanooctahedrons with mainly {101} facets were also composited with Sb8O11Cl2 and related composites displayed persistent decline in the carriers' separation efficiency and photocatalytic activity. The results can be explained by the different energy band structure of TiO2/Sb8O11Cl2 heterostructures. When Sb8O11Cl2 was composited on the {101} facets of anatase TiO2, an n-n type heterostructure will be constructed and the photo-induced electrons can hardly transform between N-type TiO2 and Sb8O11Cl2. But as Sb8O11Cl2 was composited on the {101} facets of anatase TiO2 nanosheets with coexposed {101} and {001} facets, a novel n-p-n dual heterojunction will form. In this n-p-n dual heterojunction, photo-induced electrons produced in the conduction band of Sb8O11Cl2 will flow into the conduction band of P-type {001} facets and finally flow into the {101} facets of TiO2. In this way, the photo-induced carriers will separate into different semiconductors and the photocatalytic activity of TO/Sb8O11Cl2 heterostructures is enhanced.