Fig. 4: Synthetic methodology.

a Powder XRD patterns of SC-MEHOs with different compositions and phases. HAADF-STEM EDS mapping images, TEM images and corresponding SAED patterns, and high-magnification HAADF-STEM images of b SC-MHEO-(CoNiMnCuFe)₃O₄, c SC-MHEO-(CoNiMnCuZnBi)₃O₄, d SC-MHEO-(CoNiMnCuZnFeBi)₃O₄, and e SC-MHEO-(CoNiMnCuZn)O.