Enhancement of tetracycline photocatalytic degradation under visible light: Unleashing the synergy of Z-scheme Ag₃PO₄/GCN/FeNi-BTC photocatalyst with carbon quantum dots

This study presents a novel photocatalytic composite, Ag₃PO₄/GCN/FeNi-BTC/CQD (AGF-CQD), synthesized via a green microwave-assisted hydrothermal method, integrating carbon quantum dots (CQDs) derived from aquaculture by-products. The AGF-CQD composite demonstrates superior photocatalytic activity, attributed to enhanced visible light absorption, efficient charge transfer, and improved electron-hole separation. Analytical techniques such as photoluminescence (PL), UV–Vis diffuse reflectance spectroscopy (DRS), and transmission electron microscopy (TEM) validate the composite's structural and optical properties. In tetracycline degradation tests, AGF-CQD outperforms Ag₃PO₄, GCN, FeNi-BTC, and 20 % AGF samples by 5.5, 3.6, 4.4, and 2.3 times, respectively, achieving a remarkable 98.4 % removal rate after 60 min under visible light. Factors affecting degradation, including dosage, concentration, pH, and water source, are investigated. Furthermore, an operating mechanism based on electrochemical properties and the involvement of radicals is proposed. This research offers a sustainable approach to synthesizing efficient photocatalysts for environmental remediation.