In situ synthesis of graphitic carbon nitride nanosheet/Ti3C2Tx MXene/TiO2 Z-scheme heterojunctions boosting charge transfer for full-spectrum driven photocatalytic sterilization

Abstract

The development of a full-spectrum responsive photocatalytic germicide with excellent charge separation efficiency to harvest high antimicrobial efficacy is a key goal yet a challenging conundrum. Herein, graphitic carbon nitride nanosheet (PCNS)/Ti3C2Tx MXene/TiO2 (PMT) Z-scheme heterojunctions with robust interface contact were crafted by in situ interfacial engineering. The strong internal electrical field (IEF) from PCNS to TiO2, evinced by the Kelvin Probe Force Microscopy (KPFM) characterization, can obtain high charge separation efficiency with 73.99%, compared to Schottky junction PCNS/Ti3C2Tx (PM, 32.88%) and PCNS (17.70%). The Ti3C2Tx component can not only serve as a transfer pathway to accelerate the recombination of photoexcited electrons of TiO2 and holes of PCNS under the Ultraviolet–visible (UV–vis) light irradiation, but also replenish the photogenic electron concentrations to semiconductors in the near-infrared (NIR) light illumination. Meanwhile, the increased temperature due to the localized surface plasmon resonance (LSPR) can further boost the electronic activity to the generation of reactive oxygen species (ROS). Taken together, the PMT performs a high disinfection efficiency up to 99.40% under full solar spectrum illumination, 3.88 and 9.75 times higher than PCNS and TiO2, respectively, surpassing many reported Z-scheme heterojunctions. This work offers guidance for the design of Z-scheme heterojunction with the implanting of plasmons to secure excellent full-spectrum responsive photocatalytic sterilization performance.