Variable dimensional structure and interface design of g-C3N4/BiOI composites with oxygen vacancy for improving visible-light photocatalytic properties

It is still challenging to adjust the desired structure and heterojunction interface of photocatalytic materials by a facile and efficient strategy. In this manuscript, variable dimensional structured BiOI with surface oxygen vacancies (OVs) were prepared via an in-situ growth on mesoporous g-C 3 N 4 nanosheets through one-pot synthesis at room temperature, which possesses the p-n heterojunction required for the high-performance photocatalysis . By reducing the amount of the precursor of BiOI during the reaction, the morphology of BiOI gradually changed from 3D microspheres to 2D nanosheets and even 0D nanoparticles , which were conjugated with ultrathin g-C 3 N 4 nanosheets forming the composites with 2D/3D, 2D/2D, and 2D/0D structure, respectively. The catalyst with the best performance was determined to be the g-C 3 N 4 /BiOI with 2D/2D structure, which provides a larger contact surface, appropriate bandgap, and the higher utilization of visible light. The synergies between heterostructure and OVs can promote both the production and the separation of electron-hole effectively, and hence producing more oxidizing • O 2 − and h + with the energy input. Thereby, under visible light, the optimized combination of g-C 3 N 4 /BiOI heterojunction can exhibit the outstanding photocatalytic performance of degrading 99% rhodamine B within 2 h, which was 2.6 and 12.8 times faster than pure g-C 3 N 4 and pure BiOI, respectively. In addition, our work provides a feasible and adjustable approach to regulate the structure and heterojunction interface of photocatalysts as well as the discussion about the variable dimensional structure-activity relationship in photocatalysis .