Design of 3D flowerlike BiOCl Br1 nanostructure with high surface area for visible light photocatalytic activities

A three-dimensional (3D) BiOClxBr1-x (x = 0–1) solid solutions nanostructures with compositional tunability were successfully synthesized via a one-step glycol-assisted hydrothermal process in the presence of cationic polyacrylamide (C-PAM) and cetyltrimethylammonium bromide (CTAB). The prepared samples displayed hierarchical flower-like microspheres with rich in specific surface area and appropriate pore size, providing suitable pathways for transportation and separation of photogenerated electrons and holes. The controllable ratio of Cl− and Br− led to the decrease in the optical bandgap, thus increasing the absorption of visible light range. The solid solutions delivered remarkable adsorption capacity and photocatalytic activity in comparison with pure BiOCl, BiOBr and P25 (TiO2 nanoparticles) in the photodegradation of methyl orange (MO) aqueous solution under visible light irradiation, and the degradation rate reached the maximum at x = 0.5 and decreased gradually with x moving away from 0.5. The BiOCl0.5Br0.5 sample displayed high photostability under repeated visible light irradiation, which is especially important for its practical application. Based on the above findings, the reasonable formation mechanism and the main active species of the samples were also discussed in detail.