Fig. 2: Structural and compositional characterization of Ni/Fe-MOFs.

a FT-IR spectra showing O–H (3429 cm−1), C=C (1618 cm−1), and Fe/Ni–O (540–715 cm−1) bonds. b XRD patterns highlighting amorphous C–N peaks (22°) in Ni-rich MOFs. c TG-DSC curves demonstrating thermal stability: Ni-MOFs undergo three weight-loss steps (water loss, precursor decomposition, and organic ligand degradation), while Fe-rich MOFs show two steps. d XPS full spectra confirming the presence of Fe, Ni, C, N, and O.