The efficiency of heterogeneous photocatalytic processes is currently limited due to the fast recombination of photocarriers, poor light absorption, and inefficient surface catalytic characteristics. In this study, defect-rich yellow TiO2-x nanoparticles (abbreviated as D-TiO2) with high surface area and significant absorption in the visible range were integrated with perovskite-like Bi4Ti3O12 to synthesize binary D-TiO2/Bi4Ti3O12 nanocomposites. To overcome the problem of insufficient activity, we integrated the optimized D-TiO2/Bi4Ti3O12 nanocomposite with plasmonic Bi nanoparticles. Significantly, the optimized D-TiO2/Bi4Ti3O12/Bi-2 nanocomposite efficiently removed tetracycline (TC) in 50 min through production of •OH, h+, and •O2- species, whose removal rate promoted 10.6, 3.18, 5.01, and 1.84 compared with the white TiO2 (abbreviated as W-TiO2), D-TiO2, Bi4Ti3O12, and D-TiO2/Bi4Ti3O12 (20%) photocatalysts, respectively. The outstanding performance of the D-TiO2/Bi4Ti3O12/Bi photocatalyst was attributed to its quantum dot size, low resistance for charge migration, increased surface area, oxygen vacancies in D-TiO2, and developed n-n heterojunction among D-TiO2 and Bi4Ti3O12, which accelerated charge transfer and promoted the generation of active species. Furthermore, the stability tests showed that the TC degradation efficiency still reached 96% after four recycles, indicating the remarkable stability of the photocatalyst. Eventually, the biocompatible nature of the treated solution over the optimized photocatalyst was also revealed from an investigation of the growth of lentil seeds.
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