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 (ca. 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 via 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.