Green synthesis of CuO nanoparticles using Senegalia catechu bark, leaf, and stem: Enhanced photocatalytic and antimicrobial activity

This work reports a plant-part-mediated green synthesis of copper oxide nanoparticles using bark, leaf, and stem extracts of Senegalia catechu and evaluates their photocatalytic and antimicrobial performances. The phytochemicals obtained from the plant served as intrinsic stabilizing and capping agents. A combination of ultraviolet-visible (UV-vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDS) spectroscopy was employed to analyze the bark, leaf, and stem-mediated nanoparticles, confirming their crystalline structure, functionalized surfaces, and crystallite size ranging from 32.44 to 42.16 nm. The nanoparticles’ ability to degrade methylene blue under sunlight was used to assess their photocatalytic activity, with bark-, leaf- and stem-derived nanoparticles achieving 95.14%, 97.64%, and 93.48% degradation, respectively, within 210 min. Scavenger tests were performed in order to determine which reactive species were taking part in the degradation process. After four successive cycles, reusability investigations showed that the CuO NPs maintained a degrading efficiency of over 84.08%, indicating their reusability and promise for environmentally friendly water treatment. Antimicrobial activity against both bacteria and fungi yielded inhibition zones of 11–19 mm, with bark-derived nanoparticles showing the most substantial effect. This work demonstrates that plant-part-mediated green synthesis offers an environmentally friendly strategy to produce multifunctional CuO NPs that combine efficient photocatalytic and antimicrobial performance and promote environmentally benign nanotechnology toward a sustainable future.