Integration of Bi5O7I with TiO2: Binary photocatalysts with boosted visible-light photocatalysis in removal of organic contaminants

The water pollution caused by releasing widespread organic dyes into wastewater is one of the most important concerns affecting the human life. Providing visible-light-responsive photocatalysts based on TiO2 can be noticed as a promising approach for the remedy of water contaminations. Herein, Bi5O7I nanoparticles were integrated with TiO2 to establish efficient TiO2/Bi5O7I heterojunction photocatalysts with the aid of hydrothermal method. Several complementary analyses of XRD, SEM, EDS, BET, photocurrent density, UV–vis DRS, TEM, HRTEM, PL, EIS, and XPS were applied to investigate the structure, texture, optical feature, and charge transfer efficiency of the as-prepared photocatalysts. The obtained results of the mentioned analyses revealed that the Bi5O7I particles have been successfully introduced to the surface of TiO2. The photocatalytic property of TiO2/Bi5O7I nanocomposites was evaluated by the elimination of fuchsine, MB, MO, and RhB pollutants under visible light. According to the photocatalytic tests, the binary photocatalysts manifested a prominent ability in the degradation of these pollutants than the single components. The outstanding photocatalytic ability belonged to the TiO2/Bi5O7I (15%) sample. The photocatalytic performance of TiO2/Bi5O7I (15%) was 3.8, 4.1, 3.6, and 15.1 times more than Bi5O7I and 16.8, 14.8, 18.4, and 50.5 times premier than TiO2 in the elimination of MB, fuchsine, MO, and RhB contaminants, respectively. The charge separation efficiency of the electron-hole pairs in TiO2/Bi5O7I photocatalysts was confirmed by photoelectrochemical tests. The increased surface area, boosted visible-light absorption, as well as extended lifetime of photogenerated charges have led to enhanced photocatalytic efficiency in the TiO2/Bi5O7I nanocomposites. Based on the radical trapping tests, the h+ and •O2− identified as the active species in the degradation reaction. A possible photocatalytic mechanism and photo-degradation pathway were proposed based on the outcomes obtained from the trapping experiments and photoelectrochemical analysis. Moreover, the TiO2/Bi5O7I samples exhibited good photostability over four cycles. This work presented that the TiO2/Bi5O7I photocatalysts can be a proper candidate for environmental purification. © 2021 Elsevier B.V.