Facile synthesis of Bi5O7Br/BiOBr 2D/3D heterojunction as efficient visible-light-driven photocatalyst for pharmaceutical organic degradation

BiOBr-based composite photocatalysts had attracted extensive attention for efficient photocatalytic degradation aqueous organic pollutants in the past decade. However, the catalysis ability of photocatalyst is greatly limited by their intrinsic high recombination rate of photo-generated charge carriers. Herein, we solve this problem by constructing a novel 2D/3D Bi5O7Br/BiOBr heterojunction photocatalyst that was prepared via one-step facile hydrolysis process. The pure Bi5O7Br and pure BiOBr photocatalysts were also obtained by only adjusting the pH value of the mixed solution. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical and electric property analysis and etc. The results suggested that 2D Bi5O7Br nanosheets tightly attached to the surface of BiOBr 3D structure with nanoflakes self-assembled microsphere, which could increase the transfer and separation efficiency of photogenerated charges. Furthermore, the 2D/3D Bi5O7Br/BiOBr heterojunction exhibited superior visible light photocatalytic performance for carbamazepine (CBZ) degradation than pure BiOBr and pure Bi5O7Br, which owing to the enhanced separation of photoinduced electrons and holes. At last, the underlying photocatalytic mechanism is elucidated based on the band structure and radical scavenging experiments. This work provided a feasible design idea to one-step construct 2D/3D nanocomposite for pharmaceutical wastewater purification.