Complete photodegradation of tetracycline induced by surface microenvironment of graphitic carbon nitride/silver phosphate

Silver phosphate (Ag3PO4) is a promising photocatalyst, but the photo-corrosion issue limits an effective and comprehensive photocatalysis degradation of tetracycline (TC). In this work, a unique graphitic carbon nitride-Ag3PO4 (KCN-AP(40%)) core-shell structure was prepared via a simple chemical sedimentation method. The unique graphitic carbon nitride sheet encloses Ag3PO4 to trap excited electrons from the conduction band position of Ag3PO4, suppressing the reduction of Ag+ and Ag metal deposition on the surface of Ag3PO4. Under visible light irradiation, the optimized KCN-AP(40%) can photodegrade nearby 100% of TC within 20min with a first-order kinetic constant of 0.127min-1, which is 3.34 and 3.97-folds higher than those of Ag3PO4 and graphitic carbon nitride, respectively. A series of factors that may affect photoactivity of KCN-AP (40%) including pH, inorganic ions, and organic matter are investigated. In final, the photodegradation mechanisms and intermediates were proposed based on ex-situ HPLC-MS. This work explains the deep decomposition of TC and presents a facile approach for designing and manufacturing Ag3PO4 based nanohybrids.