Z-scheme 2D/1D MoS2 nanosheet-decorated Ag2Mo2O7 microrods for efficient catalytic oxidation of levofloxacin

Abstract

Levofloxacin—a fluoroquinolone antibiotic—is a potential wastewater contaminant generated by pharmaceutical industries. Novel one-dimensional disilver dimolybdate (Ag2Mo2O7) structures were developed to form a heterojunction with thin nanosheets of MoS2 on the surface of Ag2Mo2O7. A photocatalyst was used for the efficient removal of levofloxacin under visible light. The processing of the Ag2Mo2O7 structures was optimized by altering the hydrothermal duration with structural analysis using Rietveld refinement. An enhanced catalytic activity for levofloxacin degradation (efficiency of 97%) was observed with 30 wt% MoS2/Ag2Mo2O7, following first-order kinetics. The superior activity is ascribed to the well-aligned and favorable band positions, which allowed efficient charge transfer between the photogenerated charge carriers. The direct Z-scheme led to the photogeneration of a large number of electrons at the MoS2 surface. An investigation with radical scavengers indicated that superoxide radicals played a significant role in the degradation process, which was confirmed by electron spin resonance spectral measurements. Detailed parametric studies were performed, and the reaction mechanism was examined, providing an insight into the development of such hybrid microcomposites for the removal of hazardous pharmaceuticals from the environment.