Enhanced visible photocatalytic oxidation activity of perylene diimide/g-C3N4 n-n heterojunction via π-π interaction and interfacial charge separation

Herein, perylene diimide (PDI)/oxygen-doped g-C3N4 nanosheets (O-CN) n-n heterojunction photocatalyst was prepared by an in-situ electrostatic assembling. The π-π interaction between self-assembled PDI and O-CN could lead to the electron delocalization effect to facilitate the electron migration. Self-assembled PDI could broaden the visible response range of O-CN to produce more photogenerated carries. Moreover, the interlaced band structures of O-CN and self-assembled PDI could result in a built-in electric field to promote the interfacial charge separation. Besides, many active species (h+, O2− and 1O2) could be accumulated to improve the oxidation ability of PDI/O-CN. Therefore, PDI/O-CN exhibited enhanced visible photocatalytic oxidation activities towards disinfection, degradation and oxygen evolution. The optimum PDI/O-CN inactivated 96.6% of Staphylococcus aureus cells within 3 h, while O-CN only killed 62.2%. Additionally, the phenol degradation rate and evolved oxygen amount in 2 h of PDI/O-CN-40% were 3.6 and 1.8 times as high as those of O-CN, respectively.