Study On Preparation And Photocatalytic Properties Of G-C₃N₄ And MoS₂/NiS/g-C₃N₄ Semiconductor Hybrids

Broad-spectrum antibiotics pollution in water system is becoming a major threat to human body and environment due to the discharge of pharmaceutical wastewater and the wide application of antibiotics in aquaculture and livestock. Graphitic C₃N₄ ?g-C₃N₄?has many advantages, such as non-toxicity, chemical stability and good visible light reponse, which make it a potential material for pollutants photodegradation. But the low utilization of visible light and high electron-hole pair recombination rate are still problems needing to be solved. In this study, g-C₃N₄ was prepared via a calcination condensation mthod. Binary hybrids (?MoS₂/g-C₃N₄?NiS/g-C₃N₄? and ternary hybrids?NiS/MoS2/g-C₃N₄? were synthesized via a facile hydrothermal and bathing with ultrasound methods respectively. Besides, g-C₃N₄/g-C₃N₄ homohybrids were alao prepared by calcining different precursors.In the preparation process of binary and ternary hybrids,the controlled construction of hybrids could be achieved by adjusting the weight ratios of MoS2 and NiS in MoS2/g-C₃N₄, NiS/g-C₃N₄ and NiS/MoS2/g-C₃N₄ hybrids, also categories of precursors in g-C₃N₄/g-C₃N₄ isotype hybrids. The samples were characterized by XRD, XPS, TEM,FT-IR, UV-Vis and PL methods, and both the photodegradation rate of methyl orange?MO? and antibiotics ?CIP and TC? were conducted following the dynamic analysis.The study shows that: ?1? For MoS₂/g-C₃N₄ hybrids,MoS₂ have been loaded on the surface of g-C₃N₄ successfully. The maxmum visible light photodegradation rates of CIP and TC are 82% and 100% after 4 h irradiation, and the corresponding k values are 2.3 and 1.4 that of pure g-C₃N₄. ?2? For NiS/g-C₃N₄ and NiS/MoS2/g-C₃N₄ hybrids, NiS has also been loaded on the surface of g-C₃N₄ successfully. After being irradiated for 2 h under visible light, the photodegradation rates of CIP and TC degraded by the ternary hybrid are 71.3% and 96.2%, and the corresponding kvalues are 2.8 and 3.0 that of pure g-C₃N₄, also 1.9 and 1.8 times than that of 1-NiS/C. Besides, after being used for 6 times,the photodegradation rate of NiS/MoS2/g-C₃N₄ hybrids still achieves 75.5%,showing excellent photocatalytic stability. ?3? For g-C₃N₄/g-C₃N₄ homohybrids,which have been synthesized through coupling different precursors. The photodegradation rates of g-C₃N₄/g-C₃N₄ homohybrids synthesized by Thiourea and Urea for CIP and TC degradation are 67.9% and 92.3% respectively after 4 h visible light irradiation.In this study, the controlled construction of hybrids with transition metal dichalcogenides ?NiS/MoS2? and different precuesors have improved the visible light absorption ability ?from 450 nm to 470 nm? effectively, and the matched band structures enhanced the separation rate of electrons-hole pairs. The photocatalysis mechanism models have been established and the paths of visible light activated charge transfer have been analyzed, which could provide theoretical basis and technical support for the preparation of new g-C₃N₄ photocatalytic materials.