Fabrication of interlayer β-CD/g-C3N4@MoS2 for highly enhanced photodegradation of glyphosate under simulated sunlight irradiation

Abstract

Graphitic carbon nitride (g-C₃N₄) has been considered to be a promising metal-free photocatalyst, although the high recombination rate of charge carriers and poor absorption of visible light have limited its applications. In order to overcome these problems, an interlayer composite photocatalyst that comprised β-cyclodextrin (β-CD), oxygen-doped C₃N₄ (O-C₃N₄) and molybdenum disulfide (MoS₂) was successfully constructed for the highly enhanced photodegradation of glyphosate in this study. The structure and morphology, optical properties, and photoelectrochemical properties of the prepared photocatalyst were characterized via a series of characterization techniques. The average fluorescence lifetime of the composite photocatalyst was extended from 6.67 ns to 7.30 ns in comparison with that of g-C₃N₄, which indicated that the composite photocatalyst enhanced the absorption of visible light and also inhibited the recombination of electron–hole pairs. The mass ratio of MoS₂ that corresponded to O-C₃N₄/MoS₂-5 enabled the highest removal rate under simulated sunlight irradiation, which was almost twice that achieved using pure g-C₃N₄. Relative species scavenging experiments revealed that ·O₂⁻ was the main species during the process of photodegradation. Besides, a toxicity test indicated that glyphosate became less toxic or non-toxic after photodegradation. This study provided an effective, feasible and stable photocatalyst driven by simulated sunlight irradiation for the highly enhanced photodegradation of glyphosate.