Fig. 1: Material characterizations.

a XRD patterns of CoFe LDH/NF and PW₁₂-CoFe LDH/NF. b SEM images of PW₁₂-CoFe LDH/NF. cTEM image of PW₁₂-CoFe LDH. d High-magnification AC-STEM image of PW₁₂-CoFe LDH. e Extracted AC-TEM image from (d) for detailed analysis. f Rotated view of a PW₁₂-POM molecule in a ball-and-stick model format. Gray, red, and purple spheres represent W, O, and P atoms, respectively. g STEM image and its corresponding elemental mapping images of PW₁₂-CoFe LDH. h Normalized Fe K-edge XANES spectra of PW₁₂-CoFe LDH, CoFe LDH, Fe₂O₃, FeO, and Fe foil. i Normalized Co K-edge XANES spectra of PW₁₂-CoFe LDH, CoFe LDH, Co₃O₄, CoO, and Co foil. j First derivative Fe K-edge spectra of PW₁₂-CoFe LDH, CoFe LDH, Fe₂O₃, FeO, and Fe foil. The inset shows the oxidation states of Fe for PW₁₂-CoFe LDH and CoFe LDH. k FT-EXAFS spectra of Fe K-edge for PW₁₂-CoFe LDH, CoFe LDH, Fe₂O₃, FeO, and Fe foil. Wavelet transform of k²-weighted EXAFS signals for (l) CoFe LDH and (m) PW₁₂-CoFe LDH. R represents the distance from the central atom, and K is the wavelength of the oscillation. Source data are provided as a Source Data file.