▎ 摘　　要

In this study, graphene oxide (GO) enwrapped polyimide (PI) composite photocatalyst was prepared via a facile ultrasonic chemical method. The as-synthesized GO/PI hybrid composite can serve as a stable metal-free photocatalyst for 2,4-dichlorophenol (2,4-DCP) degradation under visible-light irradiation. After loading of GO, the GO/PI composites displayed enhanced photocatalytic performance. The apparent rate constant for 2,4-DCP degradation of the composites was approximately 4.5 times as high as that of bare PI. The results of radical trapping experiments and electron spin resonance indicated that the photogenerated hole (h(+)) and O-center dot(2)- were the main responsible for the 2,4-DCP degradation. The energy band diagram derived from Mott-Schottky and UV-vis diffuse absorption spectra revealed that the formed heterojunction between PI and GO is type-II. The formed heterojunction with well matched energy levels leads to an efficient injection of photoinduced electrons from PI to GO, and facilitates the separation of photoinduced charge carrier. The combined transient photo current and electrochemical impedance spectroscopy results further verified the enhancement was mainly ascribed to the improved charge carrier separation performance of composite.