Visible-LEDs-induced enhanced photocatalytic and antibacterial activity of BiVO₄-based green photocatalysts decorated with silver and graphene

Bismuth vanadate (BiVO4) is an attractive compound because of its visible light photocatalytic activity with a narrow energy gap of less than 2.4 eV. In addition, it has favorable band edge positions and is stable in an aqueous environment. Its photocatalytic activity can be translated for potential use for degradation of organic matter. To assess this activity, BiVO4 combined with graphene (N-G/BiVO4), silver (Ag/BiVO4), or both of them (N-G/Ag/BiVO4) were synthesized. These nanostructures (NSs) were characterized using physicochemical ana-lyses. The NSs were tested for their capabilities to photodegrade crystal violet and inactivate bacteria. Results showed that N-G/Ag/BV exhibited the highest activity for degrading crystal violet, reaching 100 % of photo-degradation within 60 min of light exposure, while N-G/BiVO4, BiVO4 and Ag/BiVO4 achieved 81, 89 and 95 % within 180 min, respectively. In the case of bacterial inactivation, the Ag/BiVO4 NS completely photoinactivated E. coli within 60 min. The main oxidative species acting in the E. coli photoinactivation and CV photodegradation over the Ag/BiVO4 and N-G/AgBiVO4 NSs were identified as center dot O2- and h+. Also, the chemical stability and effective re-use of the photocatalysts were evaluated. In conclusion, the Ag/BV and N-G/Ag/BV catalysts possess high stability, making them potential candidates for wastewater treatment.