Fig. 3

FE-SEM micrographs, EDX spectrum, and elemental mapping micrographs of Co₃O₄ NPs. a, b, and c FE-SEM micrographs of biosynthesized Co₃O₄ NPs at different magnifications. d, e Types of elements, their weights, and atomic percentages in the sample of Co₃O₄ NPs produced using the biological method. f–h Elemental mapping image and abundance distribution of cobalt and oxygen elements in an electron microscope image. (f) Cobalt (Co) element, (g) Oxygen (O) element, and (h) cobalt oxide (CoO). The Co₃O₄ NPs exhibit a spherical shape and have an approximate size of 60 nm. They contain cobalt (Co) and oxygen (O) as major elements