The performance and mechanism for photocatalytic degradation of methylene blue catalyzed by ultrathin NiAl-layered double hydroxides

Abstract

Ultrathin materials are widely used in various photocatalytic reactions due to their large specific surface area, multi-surface active sites, easy carrier separation and transport. In this work, ultrathin NiAl-layered double hydroxides (U-LDHs) nanosheets were prepared by a urea-assisted strategy for photocatalytic degradation of methylene blue. Atomic force microscopy (AFM) measurements show that the thickness of U-LDHs nanosheet is generally between 3 and 8 nm, with a wide pore size distribution and a high specific surface area (109 m2/g). U-LDHs nanosheets can remove 92.42% of methylene blue after 90 min light irradiation, which is nearly 40% higher than that of bulk NiAl-LDHs (B-LDHs). In addition, combined with photoelectric performance characterization and density functional theory calculation, it is confirmed that the U-LDHs nanosheets are much better to the separation and transfer of photogenerated carriers compared with the bulk LDHs. Besides, U-LDHs is conducive to adsorb oxygen to generate superoxide radicals, promoting the progress of photocatalytic reactions and significantly improving photodegradation performance.