Hierarchical assembly of graphene-bridged Ag3PO4/Ag/BiVO4 (040) Z-scheme photocatalyst: An efficient, sustainable and heterogeneous catalyst with enhanced visible-light photoactivity towards tetracycline degradation under visible light irradiation

A novel graphene-bridged Ag3PO4/Ag/BiVO4 (040) Z-scheme heterojunction with excellent visible-light-driven photocatalytic performance was fabricated using a facile in situ deposition method followed by photo-reduction. The as-obtained nanocomposite was employed to degrade tetracycline (TC) in water under visible light irradiation. Compared to pure BiVO4, Ag3PO4 and other nanocomposites, Ag/Ag3PO4/BiVO4/RGO displayed more superior photodegradation efficiency with 94.96% removal of TC (10 mg/L) in 60 min, where the optimal conditions was catalysis dosage 0.50 g/L and initial pH at ca. 6.75. The influences of TC concentrations, light irradiation condition, coexistence ions and water sources were also investigated in details. The enhanced photocatalytic activities could be attributed to the suppression of charge recombination, high specific surface area and desirable absorption capability of Ag/Ag3PO4/BiVO4/RGO, which were in sequence confirmed by PL, PC, EIS, BET and DRS tests. The synergistic effects of RGO and Ag/Ag3PO4 in the hybrid could also contribute to the improved photo-stability and recyclability towards TC decomposition. In addition, radical trapping experiments and ESR measurement revealed that the photo-induced active species superoxide radical (O-center dot(2)-) and holes (h(+)) were the predominant active species in the photocatalytic system. The Ag/Ag3PO4/BiVO4/RGO nanocomposite also possessed desirable photocatalytic performance on the degradation of TC from real wastewater, further verifying its potential in practical industries. This work provides a promising approach to construct visible-light response and more stabilized nanocomposite photocatalysts applied in efficient treatment of persistent pollutants in wastewater. (C) 2016 Elsevier B.V. All rights reserved.