Designing heterointerface in BiOBr/g-C3N4 photocatalyst to enhance visible-light-driven photocatalytic performance in water purification

A rapid recombination of photo-generated electrons and holes is the intrinsic defect in graphitic carbon nitride (g-C3N4)-based photocatalysts. Inspired by natural photosynthesis, an artificially synthesized Z-scheme photocatalyst can efficaciously restrain the recombination of photogenerated electron-hole pairs and enhance the photoabsorption ability. Herein, a series of novel visible-light-driven (VLD) solid-state Z-scheme BiOBr/g-C3N4 heterostructured photocatalysts were successfully synthesized via a facile in-situ oxidation method which enabled the BiOBr nanosheets to grow on the surface of g-C3N4. The introduction of BiOBr on g-C3N4 to constitute a Z-scheme heterojunction system can effectively broaden the light absorption range and promote the separation of photo-generated electron-hole pairs. Besides, the Z-scheme mechanism proved by active species trapping experiments led to the persistence of photoinduced electrons in the CB of g-C3N4 while holes in the VB of BiOBr, thus ensuring the high redox ability of the charge carriers. Notably, the BC12% sample exhibited the optimized photocatalytic activity in which the RhB molecules were decomposed within 20 min under visible light irradiation, achieving 3.3- and 2.3-fold improvement than the bare g-C3N4 and pristine BiOBr, respectively. Meanwhile, the BC12% sample still revealed the superiority in both photodegrading MO and photoreducing Cr (VI). As an original strategy to obtain samples with highly dispersed heterointerface, this work could provide a facile route for the construction of g-C3N4-based solid-state Z-scheme heterojunction and very promising for practical application.

Automated summary

The rapid recombination of photo-generated electrons and holes in graphitic carbon nitride (g-C3N4)-based photocatalysts can be effectively suppressed by an artificially synthesized Z-scheme photocatalyst, which enhances photoabsorption ability and catalytic activity. The introduction of BiOBr on g-C3N4 to form a Z-scheme heterojunction system broadens the light absorption range, promotes the separation of electron-hole pairs, and shows promising potential for practical applications.