Facile assembly of g-C3N4/Ag2CO3/graphene oxide with a novel dual Z-scheme system for enhanced photocatalytic pollutant degradation

In this study, ternary catalyst g-C3N4/Ag2CO3/graphene oxide was synthesized through a simple chemical precipitation method at room temperature. The CN/AC/GO composite was employed to degrade antibiotics under visible light irradiation. And the results indicated that the composite possessed excellent photocatalytic performance, which could remove 81.6% tetracycline (TC) after 60 min of irradiation. The PL, EIS, PC and UV-vis DRS tests demonstrated that enhanced photocatalytic efficiency could be attributed to rapid charge transfer, low recombination rate of photo-induced electron-hole pairs, as well as superior light absorption capability. Moreover, three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs) were employed to further grasp the behaviors of TC molecules in the process of degradation reaction. In addition, the liquid chromatography-mass spectrometry (LC-MS) was carried out to explore the intermediates during the photocatalytic reaction. Meanwhile, the influences of initial TC concentration, light source, supporting electrolytes and water sources were explored from the perspective of practical application. Furthermore, the appearance of a small amount of Ag nanoparticles (NPs) not only accelerated the charge transfer, but also improved the stability of catalyst. The composite also possessed high stability and reusability, which were essential in practical application.