Origin of the Photocatalytic Activity of Crystalline Phase Structures

Understanding photocatalysts with different crystal structures significantly improves the activity of photocatalysts and solar-conversion materials. However, the difference in the perform-ance of various phase structures remains obscure. Despite a significant amount of gathered evidence, prior literature mainly focuses on the band and electronic structure from a thermodynamic aspect. Moreover, quantitative analyses of the differences in electron-hole dynamics between different crystalline structures are scarce but essentially desired. Herein, we constructed a research model using a simple instrument to determine the electron-hole diffusion length (LD). Furthermore, we selected five classical different crystal phase photocatalytic materials such as ZnIn2S4, TiO2, KNbO3, BiVO4, and BiPO4 as prototypes to demonstrate that LD might play a dominant role in determining their photocatalytic activities. We also observed a positive correlation between LD and catalytic activity. These results help in elucidating the origin of the photoelectric properties of the different crystal phases.