Cooperative coupling strategy for constructing 0D/2D carbon nitride composites with strengthened chemical interaction for enhanced photocatalytic applications

It is difficult for hydrophobic g-C₃N₄to construct tight heterogeneous connection with hydrophilic carbon dots (CDs), resulting in deficient charge transfer and restricted interfacial attachment between two components. Doping is an efficient strategy to firmly strengthen the hybridization of g-C₃N₄/CDs composites by inducing robust π–π conjugates or covalent chemical bonds for strong CDs anchoring to g-C₃N₄. In this work, a novel CDs anchored and S, Cl co-doped carbon nitride (CSCl-C₃N₄) nanosheet is rationally designed and successfully fabricated for strong interfacial connection of g-C₃N₄/CDs. During the formation process, chlorine atoms are doped within the CDs and C-Cl covalent bond is detected. The strong interaction anchors CDs on g-C₃N₄ and endows heterojunctions more compact connection. Systematic analyses demonstrate that CSCl-C₃N₄exhibits remarkably enhanced photocatalytic performance for water splitting. Loading 0.5 wt% CDs to S, Cl co-doped C₃N₄ achieves the optimal photocatalytic activity among a series of samples (192.49 μmol∙h⁻¹), as evidenced by 25 times that of pristine C₃N₄ for generating hydrogen. Furthermore, the composite also exhibits considerable photocatalytic activity for photodegradation of tetracycline, in which the degradation rate is 15.3 times that of pristine C₃N₄. Density functional theory calculations and experimental results are employed to investigate the doping positions of heteroatoms within composites. ∙O₂⁻ was verified for predominating during photodegradation process to remove tetracycline by radical scavenge experiments. Based on the significant performance of CSCl-C₃N₄, the possible mechanism of photocatalytic reactions is put forward. The study provides a novel perspective for modifying nanostructures and constructing heterogeneous interfaces with compact connection via combining anchoring of CDs and doping strategies. The newly fabricated CSCl-C₃N₄ is a considerable photocatalyst in multifunctional applications for solar energy conversion and pollution abatement.