Z-scheme flower-like Ag/AgCl/NiZnAl-LDH for high efficiency removal of Methylene Blue: Performance and mechanism insights

Abstract

3D flower-like NiZnAl-LDH was prepared, and then the Z-scheme Ag/AgCl/NiZnAl-LDH heterojunctions were further constructed by loading different amounts of AgCl on NiZnAl-LDH surface. The structure, morphology and photoelectric properties were characterized by a variety of advanced techniques, such as XRD, XPS, SEM, HRTEM and EIS. Furthermore, methylene blue, abbreviated MB, was used as the target pollutant, and the photocatalytic degradation activity of Ag/AgCl/NiZnAl-LDH on it was explored. Results displayed that the Ag/AgCl/NiZnAl-LDH photocatalysts displayed excellent photocatalytic degradation activity for MB dye compared with AgCl and NiZnAl-LDH, and the loading of different AgCl on the surface of NiZnAl-LDH has a considerable influence on the photocatalytic performance. The alkaline condition and low concentration of MB are more conducive to the photocatalytic degradation of MB by Ag/AgCl/NiZnAl-LDH. The photocatalytic process conforms to the first-order kinetic model with a rate constant of 0.0082 min−1, which is about 3.4 times that of AgCl and NiZnAl-LDH. Compared with AgCl and NiZnAl-LDH, it is found that Ag/AgCl/NiZnAl-LDH increases the separation rate of photogenerated electrons and holes, the photogenerated carrier recombination is inhibited, and the electrochemically active area is increased. The outstanding photocatalytic activity and stability make Ag/AgCl/NiZnAl-LDH a perfect material to ease the environmental crisis. Besides, combined with free radical trapping experiments, a possible photocatalytic mechanism was raised.