Ultrasonic synthesis of controllable thin sheet-like BiPO4 assisted by ionic liquid and Bi-MOF with enhanced visible-light photocatalytic activity

Raw materials and synthesis strategies have great influence on the morphologies and optical properties of materials. In this study, ultrasonic synthesis of controllable thin sheet-like BiPO4 with an excessive visible-light response was synthesized, using Bi-based metal-organic frameworks (CAU-17) and ionic liquid [Omim]H2PO4 as raw materials. Compared with BiPO4-H (hydrothermal, solid rod shape) synthesized using inorganic salt, BiPO4-A (agitation, thin rod-like) and BiPO4-U (ultrasonic, thin sheet-like) have better visible-light absorption capacity and narrower band gap. Under visible-light, they could degrade 27.7 % (BiPO4-H), 73.0 % (BiPO4-A), and 76.3 % (BiPO4-U) tetracycline hydrochloride at 30 min, respectively. The speedy charge transfer at the photogenerated carrier interface, large specific surface areas, and improved light adsorption greatly enhance the photocatalytic performance. Cyclic experiments exhibit that the material has good photostability and repeatability. Finally, the feasible degradation mechanism of the material was proposed via a capture experiment. This paper provides a new technique for synthesizing BiPO4 or other photocatalysts, which can be used for high-efficiency wastewater purification under visible-light.