Effect of destructive {0 0 1}-{1 0 1} heterojunction on separating photo-generated electrons and holes of anatase TiO₂

Separation behavior of photo-generated electrons and holes is systematically investigated on anatase TiO₂ with selectively etched {0 0 1} facet. Results indicate that the {0 0 1} facet etching degree and the resulted Ti³⁺ impurity centers are increased along with the F ion concentration in the acid environment. However, both the etched {0 0 1} facet and the Ti³⁺ centers have little effect on trapping the photo-generated electrons. Thus all the Au particles are photo-deposited on the {1 0 1} facet, while the etched {0 0 1} facet remains blank. The present work confirms that the {0 0 1}-{1 0 1} heterojunction is really helpful to separate the photo-generated electrons and holes. This behavior is mainly associated with the intrinsic bulk crystal structure, but not the external crystal defects.