An all-organic 0D/2D supramolecular porphyrin/g-C3N4 heterojunction assembled via π-π interaction for efficient visible photocatalytic oxidation

Herein, an all-organic self-assembled tetra(4-carboxylphenyl)porphyrin (SA-TCPP)/oxidized g-C3N4 (O-CN) heterojunction photocatalyst was successfully synthesized through an in-situ electrostatic method. As a nanocrystalline supramolecular semiconductor, SA-TCPP could sufficiently contact with the surface of O-CN nanosheets, resulting in a 0D/2D assembling heterostructure via π-π interaction. The full-spectrum responsive property of SA-TCPP could enhance the light-harvesting ability of O-CN to generate more photogenerated carries, which was a driving force for photocatalytic reaction. The well-matched band structures and the π-π interaction between SA-TCPP and O-CN could give rise to a built-in electric field and electron delocalization effect to promote the interfacial charge transfer. A large amount of highly oxidative reactive species (h+, O2− and 1O2) also could make a great contribution to the strong oxidation capacity of the heterojunction system. Compared with O-CN and SA-TCPP, SA-TCPP/O-CN exhibited greatly improved visible photocatalytic oxidation performance towards pollutants degradation, oxygen evolution and disinfection. The apparent rate constant (k) of SA-TCPP/O-CN-40% for bisphenol A degradation was 3.7 times as high as that of O-CN, while the corresponding k for phenol degradation were about 2.5 times faster than that of SA-TCPP. The oxygen evolution rate of SA-TCPP/O-CN-40% were 4.7 and 2.7 times higher than those of O-CN and SA-TCPP, respectively. Additionally, the bactericidal efficiency of SA-TCPP/O-CN-40% (62.5 %) against Staphylococcus aureus cells within 8 min was also more outstanding than those of O-CN (negligible) and SA-TCPP (55.6 %). Therefore, the enhanced photocatalytic oxidation activities of SA-TCPP/O-CN heterojunction were ascribe to the synergistic effect between O-CN and SA-TCPP.