In situ fabrication of self-assembled perylene diimide/g-C3N4 n-n heterojunction for highly efficient visible-light photocatalytic oxidation activity

• 1、School of Food Science and Technology,Jiangnan University,Wu Xi 214122

Abstract：Herein, we prepared oxygen-doped g-C3N4 nanosheets (O-CN) and perylene diimide (PDI) supermolecular nanofibers modified by terminal carboxyl group at the imides, then n-n-type organic heterojunction photocatalysis was constructed by in-situ synthesis method. After hydrothermal treatment, the surface of O-CN has positive charge, which can be effectively combined with self-assembled PDI with negative charge through electrostatic attraction. In this heterojunction system, a internal electric field is formed at the heterogeneous interface between PDI and O-CN, which is beneficial to the separation of photogenerated carriers. Meanwhile, the π-π interaction between PDI and O-CN can cause the electron delocalization effect, which is conducive to the transfer of photogenerated electrons. Compared with O-CN, PDI/O-CN heterojunction shows stronger light absorption capacity, higher separation efficiency of photogenerated electron-hole pairs, and can produce more active species (h+, •O₂-, ¹O₂ and •OH) with strong oxidation ability. Therefore PDI/O-CN composites have superior photocatalytic degradation of pollutants, oxygen production and disinfection activity. When the loading of PDI is 40 wt%, the PDI/O-CN shows the optimum photocatalytic activity. The corresponding degradation rate of phenol is 3.6 times than that of O-CN, and the evolved oxygen amount in 2 hours is about 1.8 times than that of O-CN. Moreover, almost all Staphylococcus aureus had been inactivated after 3 hours with PDI/O-CN-40%, while the disinfection rate of O-CN was only 62.2% at the same time.

Keywords： photocatalysis perylene diimide/g-C3N4 heterojunction degradation disinfection oxygen production