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In this work, a novel p-n heterojunction polyimide aerogel/BiOBr (PI/BOB) photocatalyst was successfully synthesized by combining supercritical drying and in-situ precipitation method, to degrade organic pollutants in visible light. The synthesized PI/BOB photocatalysts exhibited excellent photocatalytic activity by establishing p-n heterojunction with improved charge separation and transfer performance. Moreover, the combination of BiOBr and PI can effectively reduce the hydrophobicity of PI and help to improve its application in water pollution treatment. After a comprehensive study of the microstructure and optical properties of PI/BiOBr heterojunction, it is found that the combination of PI and BiOBr nanosheets can expand the light absorption range, and the porous PI can greatly increase the specific surface area of PI/BiOBr heterojunctions. Furthermore, XPS results showed that the electron in PI transferred to BiOBr through the concentration differences, thus generating an internal electric field (IEF) between PI and BiOBr. Under the effect of IEF, photogenerated carriers can be separated between PI and BiOBr more efficiently, which can effectively improve the photocatalytic efficiency. Photocatalytic degradation experiments showed that PI/BOB has excellent photocatalytic degradation effect on RhB, and the degradation rate of 50 mg RhB was 99% in 60 min for 20 mg catalyst. Charge transfer mechanism in heterojunction under different light conditions [Display omitted] • Successfully prepared porous polyimide aerogel with high specific surface. • Combination of organic and inorganic semiconductors by hydrothermal method. • Construction of p-n type heterojunctions facilitates electron-hole separation. • xPI/BOB has a significantly higher degradation efficiency for RhB. [ABSTRACT FROM AUTHOR]

• The visible light corresponding BiOBr nanosheets were prepared by one-step water bath heating method. • The combination of diatomic doping and nanosheet construction can promote the photocatalytic performance of BiOBr. • The BiOBr nanosheets can rapidly degrade Tetracycline hydrochloride and high concentration RhB. Designing efficient photocatalysts is essential for improving photocatalytic performance. Separation efficiency of photogenerated carriers is one of the key factors affecting photocatalytic performance. Combining the construction of two-dimensional materials with elemental doping can further improve the separation of photogenerated carriers. As expected, the performance of the samples produced by Fe and Cu co-doping was superior to that of pure BiOBr and mono-doped samples, with significant improvements in the photocatalytic degradation of both rhodamine B and tetracycline. The dopant of excess metal element atoms can form impurity energy levels in the forbidden band that effectively facilitate the separation and migration of photogenerated carriers. Meanwhile, the thin-layer two-dimensional structure can effectively shorten the bulk charge carrier transmission distance and improve the transmission efficiency. This study not only provides a simple, green and low-cost method for combining iron and copper into composites materials at same time but also confirmed that the photocatalytic performance of BiOBr was strongly influenced by different Fe and Cu contents. [ABSTRACT FROM AUTHOR]