In situ reorganization of Bi3O4Br nanosheet on the Bi24O31Br10 ribbon structure for superior visible-light photocatalytic capability

In situ synthesized 2D/2D heterojunctions often exhibit a more homogeneous mixture and stronger interface interaction, thereby providing higher interfacial charge transfer and larger interface contact area compared with 0D/2D and 1D/2D heterojunctions. Herein, novel 2D/2D Bi24O31Br10/Bi3O4Br heterojunctions with a "nanosheet-on-ribbon" hierarchical structure were fabricated via in situ reorganization of original elements in a hydrothermal process, and this method was accomplished through the intervention of NH3 center dot H2O. The Bi24O31Br10/Bi3O4Br heterojunctions exhibit outstanding visible light activity than pure Bi3O4Br and Bi24O31Br10, reaching photodegradation efficiency of 85% for sulfamethoxazole in 180 min and removal rate of 32.5% for NO in 30 min. Crystalline phases, optical absorption properties, morphologies, microstructures, and band structures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, differential reflectance spectroscopy, valence band X-ray photoemission spectroscopy, Mott-Schottky methods, density functional theory, photoluminescence spectroscopy, photocurrent analysis, and electrochemical impedance spectroscopy. The superior photocatalytic activity could be ascribed to the special structure and interface interaction between Bi3O4Br and Bi24O31Br10, thereby enhancing surface-active sites, prolonging light absorption, and promoting charge separation capability during the photocatalytic reaction. The formation mechanism of Bi24O31Br10/Bi3O4Br heterojunctions was proposed, and NH3 center dot H2O was not only a pH adjuster but also a structure-controlling agent. This work provides a reference for in situ synthesis of multi-functional 2D/2D photocatalytic nanocomposites.