MoS₂ Nanoflowers\nDecorated on Graphene\nAerogels for Visible-Light-Driven Photocatalytic Degradation of Tetracycline

Abstract

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