MoS₂ Nanoflowers Decorated on Graphene Aerogels for Visible-Light-Driven Photocatalytic Degradation of Tetracycline

Abstract

The transformation of recalcitrant pharmaceutical pollutants into products with diminished concerns via heterogeneous photocatalysis has gained considerable momentum over the past several years. However, practical applications of most semiconductor-based photocatalysts are severely restricted, attributed to insufficient visible light response pertaining to their wide band gap, ultrafast recombination of the photogenerated charge carriers, and issues corresponding to retrieval for persistent usage. Herein, rosette-like molybdenum disulfide (MoS2) nanoflowers are directly grown on the interpenetrating networks of graphene aerogels (GAs) through a facile one-step hydrothermal method, and the resulting lightweight, self-supporting composites are systematically assessed for the photocatalytic degradation of tetracycline (TC). Notably, after 120 min of exposure to visible light, ∼91% of TC is degraded over the MoS2/GAs, which is severalfold higher than pristine MoS2, standalone GA, and other contemporary photocatalysts. Based on the radical quenching assay, hydroxyl radicals and superoxide anions are the principal mediators of the photocatalytic dissociation of TC. Furthermore, the primary intermediates and residual products of the photocatalytic breakdown of TC are distinguished, and a conceivable disintegration pathway is proposed. Besides, these tailor-made hybrid aerogels can be recuperated easily and successfully reused over multiple cycles, suggesting their widespread consideration in photocatalytic wastewater treatment.