Fabrication of a coated BiVO4@LDHs Z-scheme heterojunction and photocatalytic degradation of norfloxacin

Abstract

The decahedral morphology of BiVO4 and ZnCr-layered double hydroxides (LDHs) nanosheets enables the construction of a BiVO4@LDHs Z-scheme heterojunction (BiVO4 as core and LDHs as a shell) for photocatalytic degradation of norfloxacin, typical antibiotic. The effects of initial concentration of norfloxacin, catalyst loading, reaction temperature, and pH value on the performance of photodegradation were studied. It was found that the removal of norfloxacin can reach 90.3% under the optimized conditions. The core-shell structure enhances the specific surface area, improves the energetic alignment of the band structures, and produces enough hydroxyl and superoxide radicals to degrade norfloxacin. Density functional theory (DFT) calculations show that a built-in electric field is formed between ZnCr-LDHs and BiVO4, which promotes the transfer of photogenerated electrons from the valence band of ZnCr–LDHs to the conduction band of BiVO4. This transfer accelerates the flow of photogenerated electrons and reduces the recombination of electron-hole pairs, so that BiVO4@LDHs heterojunction shows excellent photocatalytic activity for norfloxacin.