2D MoS₂/Cu₂O on 3D mesoporous silica as visible-NIR nanophotocatalysts for environmental and biomedical applications

Nanostructures based on transition metal dichalcogenides have attracted considerable attention due to their tunable optoelectronic properties and large surface areas, showing a great potential as photocatalysts. Here, a novel supported structure based on 2D-MoS₂/Cu₂O nanoflakes grown on 3D mesoporous silica templates fabricated by a combination of solvothermal synthesis and e-beam deposition methods is presented. The synthesized MoS₂ nanoflakes exhibited a combination of trigonal-prismatic 2H and distorted-trigonal 1T' phases, which contributed to a high density of active catalytic sites, facilitating efficient photogenerated charge transfer to analytes at the liquid interface. The deposition of Cu on the MoS₂ nanoflakes enabled the formation of a semiconducting MoS₂/Cu₂O heterostructure with greatly enhanced photocatalytic activity. The supported MoS₂/Cu₂O nanoflakes showed excellent stability and an efficient generation of reactive oxygen species (ROS) with white and near infrared (NIR) light. The photocatalytic potential of the MoS₂/Cu₂O nanoflakes was established by the nearly complete degradation and mineralization of two organic pollutants (the antibiotic tetracycline and the biotoxin anatoxin-A) under low intensity white light, using ultralow catalyst concentration (<i>ca.</i> 4 μg mL^-1). In addition, the use of MoS₂/Cu₂O nanostructures as photodynamic agents under low intensity NIR light was demonstrated. The NIR illuminated MoS₂/Cu₂O nanoflakes, placed at a distance of 120 μm from cultured cancer cells, enabled the complete elimination of cells <i>via</i> apoptosis, despite the large separation between them. These results underline the high photocatalytic activity of the supported MoS₂/Cu₂O nanoflakes to produce ROS with visible and NIR light, thus highlighting their suitability for environmental remediation and biomedical applications.