Facile integration of brown TiO2−x with Bi4V2O11 and BiVO4: Double S-scheme mechanism for exceptional visible-light photocatalytic performance in degradation of pollutants

Abstract

Heterogeneous photocatalysis has been denoted as a promising approach to dealing with environmental and energy crises. Herein, quantum dots (QDs) of TiO2−x/Bi4V2O11/BiVO4 (TOVBBV) heterojunction photocatalysts were successfully synthesized through a facile one-pot hydrothermal process with varying amounts of integrated Bi4V2O11 and BiVO4 semiconductors. The resultant photocatalysts were characterized by XPS, FT-IR, EDX, XRD, PL, EIS, SEM, TEM, HRTEM, BET, and UV–vis DRS techniques, and their photocatalytic efficiencies were examined via removing tetracycline (TC), azithromycin (AZi), and rhodamine B (RhB) under visible-light illumination. The results showed exceptionally promoted photocatalytic degradation efficiencies of the studied pollutants using the ternary TOVBBV-2 nanocomposite. The TOVBBV-2 nanocomposite was 45.4, 11.6, and 19.8-times more effective than TiO2, 7.24, 5.85 and 2.34-folds better than TiO2−x, and 9.81, 9.23, and 1.61-times more effective than Bi4V2O11/BiVO4 for photooxidation of TC, AZi, and RhB, respectively. The significant enhancement in the photocatalytic efficacy of the TOVBBV-2 nanocomposite originated from the defective oxygen sites in the titanium dioxide structure, which subsequently facilitated the transfer of photo-induced charge carriers through the formed tandem n-n heterojunctions amongst TiO2−x, Bi4V2O11, and BiVO4 components. In addition to high photocatalytic activities, the TOVBBV-2 photocatalyst demonstrated good photostability and durability after concurrent applications. This work recommends the TOVBBV photocatalyst for facile photocatalytic treatment of pollutants owing to its simple preparation route, high degradation outcomes, and robust structure for practical applications.