Fig. 2: Atomic structure and elemental distribution of Ru_(SA)-OMS and Ru_(SA)-NiOMS.

TEM image of as-synthesized a Ru_(SA)-OMS and b Ru_(SA)-NiOMS nanorods. Atomic-resolution aberration-corrected high-angle annular dark-field (HAADF-STEM) images of the c Ru_(SA)-OMS and d Ru_(SA)-NiOMS nanorods viewed sideways along the [110] direction. The Violet spot indicates Mn atoms, green represents Ni, and orange indicates Ru atoms. e Perspective view of cryptomelane OMS along [001] direction. Ni ions are surrounded by eight [MnO₆] octahedra, forming a tunnel that extends along the [001] direction. Rotating along the a-axis presents an atomic model structure of the original STEM image. f HAADF-TEM image and element mapping images of Ni, Mn, O and Ru. FT-EXAFS spectra of the g Ru and h Mn K edge (a.u.: arbitrary unit). i Crystal orbital Hamilton population (COHP) analysis on the adjacent Mn, Ru, Ni sites of Ru_(SA)-OMS and Ru_(SA)-NiOMS, and the corresponding integrated crystal orbital Hamiltonian population (ICOHP) values.