Efficient Visible-Light-Responsive Ag₃PO₄/g-C₃N₄/Hydroxyapatite Photocatalyst (from Oyster Shells) for the Degradation of Methylene Blue: Preparation, Properties and Mechanism

A novel ternary Ag3PO4/g-C3N4/hydroxyapatite photocatalyst was prepared, and its morphology, composition and structure were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and electron spin resonance, etc. The results show that g-C3N4 is evenly dispersed in the interior of hydroxyapatite, forming a homogeneous composite, and significantly improves the band gap structure of the material as a whole. Ag3PO4/g-C3N4/hydroxyapatite has good electron transfer ability and an appropriate energy band structure, which shows that the material has a good degradation effect and stability. Finally, based on the characterization and experimental results, a possible Z-scheme mechanism was proposed, and the active species involved in the reaction are mainly ·O2− and h+