Rational design of visible-light-sensitive Ag-BiVO4 oxides by matching redox potentials of catalyst, dyes, and reactive oxygen species towards more efficient photocatalytic degradation

Abstract By employing a rational design approach of matching redox potentials of dye, catalysts, and reactive oxygen species (ROS), Ag-BiVO4 photo-catalysts of 2, 5 and 7 wt% Ag were successfully prepared via sol-gel and UV photo-reduction methods. The as-prepared composites over-perform existing counterparts by exhibiting excellent photocatalytic properties towards degradation of cationic methylene blue (MB, 20 min, 90.9 ± 2.4 %), brilliant green (BG, 20 min, 84.0 ± 2.7 %) and rhodamine B (RhB, 120 min, 90.5 ± 3.3 %) as well as anionic acid red 1 (AR, 60 min, 79.0 ± 2.5 %) and methyl orange (MO, 120 min, 64.9 ± 2.0 %) dyes. Furthermore, based on our novel approach of rational design, the degradation of MB dye was ascribed to photoelectrons from n-type BiVO4, while degradation of MO and AR was attributed to photo-holes from p-type Ag2O. Meanwhile, BG and RhB dyes degrade due to photoelectrons and photo-oxidation by ROS, which was confirmed by carrier scavenger experiments. Results indicate that Ag-BiVO4 oxide can be efficiently used for wastewater treatment, solar energy, water splitting, and medicine.