Polar semiconductor photocatalysts with intrinsic electric fields for selective organic transformation

Abstract

Semiconductor photocatalysts have been widely investigated in the field of selective organic transformation. However, the practical application of photocatalysts is greatly limited due to their low charge separation efficiency. Recently, electron–hole separation using intrinsic electric field of polar semiconductors has attracted much attention. Polarity exists widely in polar noncentrosymmetric (NCS) materials, such as piezoelectric, pyroelectric and ferroelectric materials. In the crystal structure of NCS materials, the asymmetric arrangement of ions or ion groups leads to the distribution of positive and negative charges on the surface in opposite directions, which could effectively separate the electron–hole pairs. This perspective summarized recent progress in the synthesis and photocatalytic application of polar semiconductors for selective organic synthesis. This paper also briefly introduces the working mechanism of a light free or vibration catalyst (piezoelectric catalyst). Generally, this perspective mainly focuses on five kinds of polar semiconductors, including CdS, ZnO, ABO₃, bismuth layered materials and two-dimensional polar materials. The challenges encountered, as well as the current and future scopes of this field are also discussed in this perspective.