Binary metal–organic framework composites as environmentally friendly photocatalysts: Green synthesis and visible light-assisted pollutant degradation

Green synthesis of MOF-on-MOF is an effective method to prepare the environmentally friendly photocatalyst using metal–organic frameworks (MOFs). Herein, ZIF-8 was synthesized on MIL-100 (Fe) (ZM composites) with different weight percent ratios of ZIF-8 and denoted as ZM21, ZM11 and ZM12. They were investigated as environmentally friendly photocatalysts for the degradation of Methylene Blue (MB) using visible light. XRD, FT-IR, SEM, EDX, and DRS were used to characterize the synthesized materials (ZIF-8, MIL-100, ZM21, ZM11, and ZM12). The ZM11 composite had the highest dye degradation ability. The MB photocatalytic degradation for the ZIF-8, MIL-100, ZM21, ZM11, and ZM12 were 12.59%, 31.27%, 29.45%, 86.3, and 31.51%, respectively. MB degradation by ZM11 composite followed the first-order kinetic model. The effective radical for the MB photocatalytic degradation was the superoxide radical (•O₂^–). The ZM11 composite had the ability of 76% dye removal from water after 3 cycles of MB degradation.