Preparation of P-Doped g -C3N4/MoS2/ZnO Ternary Double Z-Scheme Heterojunction with Enhanced Photocatalytic Performance for Rhodamine B Degradation

Abstract

With the rapid development of industrialization, organic pollution in aquatic environments has emerged as a major environmental concern. Herein, a ternary P-doped g-C3N4/MoS2/ZnO (PCNMZ) heterojunction photocatalyst was rationally designed and fabricated using melamine, 2-aminoethylphosphonic acid, MoS2, and ZnO as building blocks. The composites were systematically characterized by XRD, SEM, TEM, XPS, UV–vis diffuse reflectance spectroscopy, photoluminescence, and electrochemical techniques. Photocatalytic performance was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation, and the underlying mechanism was explored via radical scavenging tests. The results demonstrate that P doping effectively tailors the electronic structure of g-C3N4, while the two-dimensional layered structure of MoS2 provides intimate interfacial contact and accelerates charge transfer. The optimized PCNMZ30% sample achieves an RhB degradation efficiency of 75.64% under visible light, 5.2 times higher than that of pure ZnO. Moreover, the photocatalytic activity decreases by only 3.86% after five consecutive cycles, demonstrating excellent stability and reusability. Radical trapping experiments identify •O2– as the dominant reactive oxygen species. On the basis of band structure analysis, a MoS2-mediated double Z-scheme charge transfer pathway is proposed, which effectively suppresses electron–hole recombination and preserves strong redox potentials. This work provides a feasible strategy for designing high-performance ZnO-based photocatalysts toward environmental remediation.