Microemulsion–Assisted Synthesis of Ag2CrO4@MIL–125(Ti)–NH2 Z–Scheme Heterojunction for Visible–Light Photocatalytic Inactivation of Bacteria

Metal–organic frameworks (MOFs) are new porous materials composed of metal centers and organic ligand bridges, which received great attention in the field of photocatalysis. In this work, Ag2CrO4@MIL–125(Ti)–NH2 (denoted as AgCr@M125) Z–scheme heterojunctions were synthesized via a simple microemulsion method, by which highly dispersed nano–sized Ag2CrO4 can be anchored uniformly on the surfaces of porous MIL–125(Ti)–NH2 (denoted as M125). Compared with pure M125 and Ag2CrO4, the as–prepared AgCr@M125 hybrids show significant photocatalytic efficiency against inactivated Staphylococcus aureus (S. aureus), reaching over 97% inactivation of the bacteria after 15 min of visible light irradiation. Notably, the photocatalytic activity of the obtained 20%AgCr@M125 is about 1.75 times higher than that of AgCr–M125, which was prepared via a traditional precipitation method. The enhanced photocatalytic antibacterial activity of the AgCr@M125 photocatalytic system is strongly ascribed to a direct Z–scheme mechanism, which can be carefully discussed based on energy band positions and time–dependent electron spin response (ESR) experiments. Our work highlights a simple way to enhance the antibacterial effect by coupling with Ag2CrO4 and M125 via a microemulsion–assisted strategy and affords an ideal example for developing MOFs–based Z–scheme photocatalysts with excellent photoactivity.