Sustainable copper doped carbon quantum dots: Ultra-fast, complete photodegradation of tetracycline under visible light

Abstract

A rapid and complete photodegradation method for tetracyclines (TC) is developed in this study. TC, a class of widely used antibiotics, are detected in various environmental compartments, posing risks to aquatic ecosystems, soil fertility, and ultimately human health via the food chain. Copper-doped carbon quantum dots (Cu-CDs) were synthesized via a one-step low-temperature pyrolysis method using cost-effective disodium copper ethylenediaminetetraacetate (Na2[Cu (EDTA)]) as a precursor. Under visible light irradiation, Cu-CDs achieved 72 % TC degradation within 5 min and complete degradation (100 %) within 40 min—a 4.9-fold improvement over pristine carbon quantum dots (CDs). The morphology, chemical composition, and optical properties of the Cu-CDs were systematically characterized using TEM, AFM, XRD, FTIR, XPS, BET, UV–Vis DRS, PL spectroscopy, photocurrent response, EIS, and ESR analysis. The photocatalyst demonstrated excellent stability, maintaining 80 % of its initial activity after three consecutive reaction cycles. Mechanistic studies confirmed that photogenerated holes (h+) and superoxide radicals (•O2−) are the dominant reactive species driving TC degradation. These results demonstrate that Cu-CDs are a low-cost, stable, and highly effective photocatalyst for the rapid elimination of antibiotic contaminants, offering promising potential for wastewater treatment applications.