A novel g-C3N4 nanosheet/Ag3PO4/α-Bi2O3 ternary dual Z-scheme heterojunction with increased light absorption and expanded specific surface area for efficient photocatalytic removal of TC

A novel ternary dual Z-scheme 2D g-C3N4 nanosheet/Ag3PO4/α-Bi2O3 (CNN/AP/BO) photocatalyst was successfully synthesized by an in situ deposition and hydrothermal–calcination method. The coupling of AP and BO remarkably enhanced the photocatalytic tetracycline (TC) degradation under visible light illumination, with an optimal removal efficiency of 91.6% (60 min), which can be attributed to the extended visible-light absorption and increased specific surface area owing to the interfacial intimate coupling with well-matched energy band positions between semiconductors. The improved photocatalytic activity resulted from the abundant free radicals by the order of ˙O2− > h+ > ˙OH based on the electron spin resonance (ESR) and quenching experiment results. In addition, the possible mechanism of TC degradation over the ternary dual Z-scheme heterojunction CNN/AP/BO was proposed.