Green Synthesis of Metal Oxide Nanoparticles Using Plant Extracts with Emphasis on Vigna unguiculata (Cowpea): A Review

The green synthesis of metal oxide nanoparticles is received increasing attention due to its offer more environmentally safe alternative compared to conventional chemical methods, with many promising applications. This review focuses on usage of Vigna unguiculata (cowpea) in biosynthesis of metal oxide nanoparticles by showing its role as sustainable and low-cost reducing and stabilizing agent. The synthesis procedure is described, with emphasis on function of plant phytochemicals which help in the formation of nanoparticles. Different characterization methods are discussed, like field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and UV–Vis spectroscopy, to identify structure, morphology, and chemical nature of the nanoparticles. The review also considers the challenges associated with scaling up green synthesis processes and suggests future research directions to improve practical applications. By addressing these aspects, this review aims to provide a better understanding of the synthesis mechanisms, key properties, and real-world applications of metal oxide nanoparticles produced using Vigna unguiculata, thereby supporting the growing field of green nanotechnology.