Dual S-Scheme TiO_2–x/BiOI/BiSI Photocatalysts with Boosted Visible-Light-Activated Efficiency for Removal of Contaminants

Novel TiO_2–x/BiOI/BiSI (TovBSOI) nanocomposites, as visible-light-active materials, were constructed by a one-pot hydrothermal approach. Among the samples, the TovBSOI-2 nanocomposite displayed a higher photocatalytic efficiency upon visible light for tetracycline (TC), methyl orange (MO), rhodamine B (RhB), and azithromycin (Azi) degradations. The photoactivity of this ternary sample was almost 6.33-, 13.2-, 15.8-, and 17.9-fold greater than that of the bare TiO_2–x(Tov) and about 23.4-, 18.8-, 21.2-, and 28.6-fold higher than that of the BiOI/BiSI (BSOI) photocatalysts in removal of TC, RhB, MO, and Azi pollutants, respectively. These improvements were related to the boosted absorption of visible illumination, enhanced photogenerated carrier separation, high crystallinity, and increase in the specific surface area. The important reactive species produced over the TovBSOI photocatalytic system were evaluated, and a photocatalytic improvement mechanism was reasonably elaborated based on the experimental observations. Moreover, the stability and biocompatibility of the TovBSOI-2 sample were affirmed through four reuse cycles and wheat seed growth in the treated solution, respectively. Thus, superior photocatalytic performance and recyclability make the TovBSOI nanocomposite a nominee to solve environmental crises.