Construction of Z-scheme Ag-AgBr/BiVO4/graphene aerogel with enhanced photocatalytic degradation and antibacterial activities

The construction of heterojunctions in composite is considered to be one of the most effective methods for improving photocatalytic activity. Herein, a novel three-dimensional (3D) porous Z-scheme Ag-AgBr/BiVO4/graphene aerogel (Ag-AgBr/BiVO4/GA) photocatalyst was fabricated via a facile hydrothermal method. The asprepared Ag-AgBr/BiVO4/GA is good for electron separation and charge transfer in the water purification owing to the 3D macroscopic porous structure and high conductivity of GA. In addition, the GA is well modified by BiVO4 nanocrystals and the highly dispersed AgBr nanoparticles as well as formed a heterojunction, which effectively promotes the absorption of visible light and separation of photo-generated carriers. Benefiting from the unique composition and structure, the Ag-AgBr/BiVO4/GA exhibited excellent photocatalytic degradation efficiency for methyl orange (93.92 % removal rate in 24 min) and significant disinfection activity for E. coli or S. aureus (100 % antibacterial efficiency in 24 min) under visible light irradiation. Furthermore, on account of the chelation of chitosan (CS), the Ag-AgBr/BiVO4/GA renders wonderful recycle stability (6.3 % mass loss) for methyl orange after eight degradation cycles and the degradation efficiency remain at 91.84 %.