Biogenic CuO-ZnO nanocomposites synthesized from Jatropha curcas for methylene blue dye degradation

The growing demand for sustainable nanomaterial synthesis has driven the development of green, bio-mediated approaches. In this study, CuO-ZnO nanocomposites (Cu_xZn_1−xO; x = 0, 0.025, 0.05, 0.075, and 0.1) were synthesized via a phytochemical using the latex of Jatropha curcas an underexplored natural source as a reducing, capping, and stabilizing agent. This eco-friendly, latex-assisted approach avoids toxic chemicals and harsh synthesis conditions, making it fully compliant with green chemistry principles. The synthesized nanocomposites were systematically characterized to assess their structural and physicochemical properties. X-ray diffraction (XRD) confirmed the formation of a predominant hexagonal wurtzite ZnO phase with a secondary monoclinic CuO phase. Field emission scanning electron microscopy (FE-SEM) revealed quasi-spherical nanoparticles with well-defined facets, while energy-dispersive X-ray spectroscopy (EDS) verified the successful incorporation of Cu and Zn. Zeta potential analysis, UV–Visible spectroscopy, and FT-IR spectroscopy provided further insights into colloidal stability, optical properties and surface functionalities respectively. Among the synthesized materials, Cu_0.05Zn_0.95O exhibited the highest photocatalytic activity, achieving 88.7 % degradation of methylene blue with a kinetic rate constant of 0.01831 min⁻¹. Reusability tests and scavenger studies confirmed the catalyst's durability and mechanistic reliability. To the best of our knowledge, there are very few or no reports employing Jatropha curcas latex for Cu-doped ZnO synthesis, particularly targeting photocatalytic applications, thereby demonstrating a novel eco-friendly pathway. Overall, this work demonstrates the efficacy of Jatropha-assisted green synthesis for producing stable and efficient CuO-ZnO nanocomposites, offering a promising solution for the photocatalytic treatment of dye-contaminated wastewater.