Double charge carrier mechanism through 2D/2D interface-assisted ultrafast water reduction and antibiotic degradation over architectural S,P co-doped g-C3N4/ZnCr LDH photocatalyst

Abstract

The fabrication of a constructive heterostructure and thus the induced 2D/2D interfacial phase indicates great importance in semiconductor based photocatalysts. The energetic electrostatic force of interactions between the positively charged 2D ZnCr LDH nanosheet and the negatively charged 2D S,P co-doped g-C₃N₄ helps to form a robust heterostructure. By doping S and P simultaneously into the g-C₃N₄ matrix, the band potentials have been easily engineered for wide range visible light harvesting in comparison to the pure g-C₃N₄. This innovative 2D/2D S,P co-doped g-C₃N₄/ZnCr LDH heterostructure interface provides a high surface area and suitable redox potentials for various photocatalytic reactions. The as-fabricated S,P-g-C₃N₄/ZnCr LDH heterostructure shows considerable enhanced photocatalytic performance for the degradation of ciprofloxacin (95% in 90 min) and H₂ evolution (1319 μmol per 2 h) under visible light irradiation as compared to the pure material (g-C₃N₄, S,P-g-C₃N₄, and LDH nanosheet) and mono-doped heterostructure. The enhanced photocatalytic activities attributed to the loading of the ZnCr LDH nanosheet onto the surface of the S,P co-doped g-C₃N₄ allows effective interfacial charge mobility and transfer through intimate 2D/2D interfacial contact. In addition, the co-doping also generates some defect sites in the heterostructure that act as trapping centers for photogenerated charge pairs and the excess unpaired electrons of S and P atom delocalized in the π-conjugated triazine ring, constructing a rich-electron state, which is beneficial for the photocatalytic process. XRD, FTIR, and TEM studies of the reused composite show that the heterostructure hybrid material is very stable and can be reused many times. Our innovation in the fabrication, design, and physicochemical behaviours of the 2D/2D heterostructure may get utilized in different photocatalytic performances towards antibiotic degradation and H₂ production.