Co-assembled MoS₂-TiO₂ Inverse Opal Photocatalysts for Visible Light-Activated Pharmaceutical Photodegradation

Heterostructured photocatalytic materials in the form of photonic crystals have been attracting attention for their unique light harvesting ability that can be ideally combined with judicious compositional modifications toward the development of visible light-activated (VLA) photonic catalysts, though practical environmental applications, such as the degradation of pharmaceutical emerging contaminants, have been rarely reported. Herein, heterostructured MoS₂-TiO₂ inverse opal films are introduced as highly active immobilized photocatalysts for the VLA degradation of tetracycline and ciprofloxacin broad-spectrum antibiotics as well as salicylic acid. A single-step co-assembly method was implemented for the challenging incorporation of MoS₂ nanosheets into the nanocrystalline inverse opal walls. Compositional tuning and photonic band gap engineering of the MoS₂-TiO₂ photonic films showed that integration of low amounts of MoS₂ nanosheets in the inverse opal framework maintains intact the periodic macropore structure and enhances the available surface area, resulting in efficient VLA antibiotic degradation far beyond the performance of benchmark TiO₂ films. The combination of broadband MoS₂ visible light absorption and photonic-assisted light trapping together with the enhanced charge separation that enables the generation of reactive oxygen species via firm interfacial coupling between MoS₂ nanosheets and TiO₂ nanoparticles is concluded as a competent approach for pharmaceutical abatement in water bodies.