Efficient visible-light-photocatalytic sterilization by novel Z-scheme MXene/TiO2/Bi2S3

Photocatalytic sterilization has been recently realized as a competitive strategy for effective water purification just using sunlight, for which the new photocatalytic materials play the key role. In this study, a novel Z-scheme heterojunction material MXene/TiO2/Bi2S3 was proposed, where TiO2 nanoparticles and Bi2S3 microspheres were uniformly distributed on the MXene nanosheets through facile hydrothermal oxidation and ultrasonic dispersion. With this Z-scheme heterojunction MXene/TiO2/Bi2S3, effective and quick sterilization of both Gramnegative bacteria and positive bacteria in only 120 min was realized. Especially, the apparent reaction constant for S. aureus reached 0.01659 min(-1), substantially higher than MXene and other related materials in literature. This could be ascribed to the narrow band gap (1.04 eV), the wide range of light absorption range (420 nm), and the low impedance of the as-obtained composite, facilitating the transfer and separation of photo-generated charges, which was also validated through the first-order kinetic model and DFT simulation calculations. Thus, the reactive species produced by photocatalysis effectively disrupted the defense action of the bacteria by damaging bacterial membrane structure, and reducing enzyme activity as well as cellular metabolism. This efficient and low-cost material for water disinfection has a great potential for practical applications in the future.