Eco-Friendly Synthesis of Zn-Doped CuO Nanoparticles Using Aloysia citrodora Extract for Highly Efficient Fenton-like Dye Degradation

The development of efficient, sustainable, and low-cost catalysts for wastewater treatment remains a major environmental challenge. In this work, Zn-doped CuO nanostructures were successfully synthesized via a green route using Aloysia citrodora leaf extract as a natural reducing and stabilizing agent. The structural and morphological properties of the prepared catalysts were systematically characterized by XRD, Raman spectroscopy, FTIR, SEM, and EDX analyses. The results revealed the formation of highly crystalline monoclinic CuO nanoparticles, whose defect density and surface properties were significantly modified by Zn incorporation. The catalytic performance of the synthesized materials was evaluated through the heterogeneous Fenton-like degradation of Rhodamine B in aqueous solution under dark conditions. The Zn-doped CuO catalyst exhibited outstanding degradation efficiency (~99.97%) within only 30 min, using a low catalyst dosage of 15 mg and a minimal H2O2 amount of 25 μL. The enhanced catalytic activity is attributed to the synergistic interaction between Zn-induced lattice defects and the Cu2+/Cu+ redox cycle, which promotes efficient H2O2 activation and •OH radical generation. Radical scavenging experiments confirmed the dominant role of hydroxyl radicals in the degradation process. Compared with previously reported CuO-based catalysts, the present system demonstrates superior performance in terms of reaction rate, oxidant consumption, and energy efficiency. These findings highlight the potential of Zn-doped CuO synthesized via green chemistry as a promising and sustainable catalyst for advanced wastewater treatment applications.