Construction of Z-scheme CoAl-LDH/Bi2MoO6 heterojunction for enhanced photocatalytic degradation of antibiotics in natural water bodies

Abstract

Heterojunction construction is considered to be an effective method for improving photocatalytic efficiency. Herein, Z-scheme heterojunction CoAl-LDH/Bi2MoO6 was synthesized by a simple hydrothermal method. Due to the strong hydrolysis ability of Bi3+ made the solution acidic, to prevent the solution of CoAl-LDH, the reaction solution was adjusted to neutral by NaOH solution. The prepared materials were characterized by a series of analytical techniques and their photocatalytic performance was evaluated by photocatalytic degradation of antibiotics under natural aqueous conditions (seawater and the water from the Xiangjiang River). The composite with 10% CoAl-LDH (CBA-10) displayed the optimal degradation efficiency and still had good photocatalytic activity in seawater and Xiangjiang water compared to the pure water for degradation of antibiotics. According to the photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) test results, the heterojunction formed between CoAl-LDH and Bi2MoO6 effectively promoted the separation and migration of electrons and holes, thus increasing the photocatalytic degradation efficiency. In addition, the degradation efficiency of the composite with 10% CoAl-LDH under pure water conditions was 85.98% and 72.69% for tetracycline and ciprofloxacin respectively after five cycles of testing, which showed that the composite with 10% CoAl-LDH had good stability and reusability. This work would contribute to the development of composite materials for photocatalytic degradation of contaminants in natural water bodies.