The photocatalytic degradation and mechanism of rhodamine B by Zn–Al layered double hydroxide

Zn–Al layered double hydroxides (Zn–Al LDHs) with a typical layered structure were successfully synthesized by the hydrothermal method. The effects of molar ratios of Zn and Al on the structure, morphology, chemical composition and photocatalytic performance of Zn–Al LDHs were systematically investigated. By adjusting the Zn/Al molar ratio, it can be found that the Zn–Al-LDH-3 sheet with the ratio of 3 exhibits the best photocatalytic activity and reusability, which is mainly ascribed to the formation of more photo-generated holes in the photocatalytic process proved by the free radical quenching experiment. The optimized conditions of catalyst dosages, rhodamine B (RhB) concentrations and initial pH values to achieve the highest were also investigated in detail. This work provides a simple method for designing environmental friendly layered double hydroxide photocatalysts with special morphologies.