Dimensional-matched two dimensional/two dimensional TiO₂/Bi₂O₃ step-scheme heterojunction for boosted photocatalytic...

A Step-scheme (S-scheme) heterojunction can regulate the directional migration of powerful photogenerated carriers and realize high photocatalytic activity. Herein, we propose a novel dimensional matched S-scheme photocatalyst comprising of two-dimensional (2D) TiO₂ nanosheets and 2D Bi₂O₃ nanosheets for environmental and energy applications, such as water sterilization and water splitting. X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance, in-situ irradiated XPS and theoretical calculations provided strong evidence that the photocarrier migration in the TiO₂/Bi₂O₃ composite followed the S-scheme mode, which efficiently prevented the recombination of powerful photocarriers, thereby enabling the heterojunction with a strong redox ability for producing abundant reactive oxygen species. The tight and large 2D/2D interface minimized the distance of photocarrier migration to further extend the lifetime of useful photocarriers (active radicals for sterilization and photoelectrons for H₂ generation). The 2D/2D TiO₂/Bi₂O₃ heterojunction demonstrated an improved photocatalytic antibacterial performance with complete inactivation of 4.63 × 10⁷ CFU mL^-1Escherichia coli cells within 6 h in water. In addition, the heterojunction displayed a H₂ generation rate of 12.08 mmol h^-1g^-1 through water splitting process. This study provides a potential bifunctional photocatalyst for minimizing the adverse impact of pollution on the environment.