Embedding few-layer Ti₃C₂T_x into alkalized g-C₃N₄ nanosheets for efficient photocatalytic degradation

Solution of the increasingly important problem of aquatic pollution requires the use of an economical, energy-efficient, highly effective and environmentally-friendly catalyst. Polymeric carbon nitride (C₃N₄) has shown to be a promising metal-free photocatalyst that however suffers from strong charge recombination and poor conductivity, while MXenes have shown to be perfect co-catalysts for the photocatalytic process but show poor stability. In this study, we successfully constructed a robust heterostructure photocatalyst in which few-layer Ti₃C₂T_x was embedded into alkalized C₃N₄ without being oxidized. The photocatalyst showed stable and effective photocatalytic performance for the removal of tetracycline hydrochloride and other organic compounds under visible light irradiation. Different characterization methods were used to elucidate the morphology and structure of the as-prepared photocatalyst. The robust heterostructure and the intimate interaction between the two constituents of the composite were verified. Based on the van der Waals heterostructure, Ti₃C₂T_x acts as the electron acceptor and helps to form Schottky junction, preventing charge recombination of the photocatalyst. And in the meantime, the electrons from C₃N₄ protect Ti₃C₂T_x from oxidation. SEM and XRD results demonstrated that the Ti₃C₂T_x structure remains unchanged after calcination and after photodegradation experiments. Furthermore, a possible mechanism for photocatalytic tetracycline hydrochloride degradation was proposed based on the results of radical scavenging experiments. This work provides a strategy to strengthen heterostructure between 2D materials, and shows that carbon nitride and Mxenes could be promising materials for photocatalytic wastewater pre-treatment applications.