Figure 3: Characterization for atomic structure of the PHNCMs.
(a–c) The k3-weighted FT spectra of XANES from EXAFS at the Ni, Co and Mo K-edge of the PHNCMs and Ni foil, NiO, Co foil, CoO, 2H phase MoS2 foil as contrasting samples. A large quantity of Ni-Ni bond and tiny amount of Co-Co bond possess the major contribution in 0H-PHNCMs. Ni-O or Ni-N and Co-O or Co-N are the main bond for Ni and Co in PHNCMs with HZH. The third and fourth peaks at ∼2.40 Å and ∼2.85 Å of 0H-PHNCMs and 0.05H-PHNCMs for Mo-Mo bond indicate that 1T and 2H phase MoS2 coexist in the samples. The disappearance of the fourth peaks at ∼2.85 Å of 1H and 2.5H-PHNCMs illustrates the complete phase transformation of MoS2 to metallic 1T phase. The smoothing XPS spectra showing the binding energies of (d) Mo and (e) S in the PHNCMs. Obvious downshifts (∼1 eV) of Mo 3d and S 2p peak positions demonstrates the phase transformation from 2H to 1T phase. (f) The smoothing XPS spectrum of Mo 3d orbitals in MoS2 synthesized in the same way as PHNCMs. With the increasing quantity of HZH, the peaks of Mo 3d3/2 and Mo 3d5/2 orbitals in MoS2 have slight downshifts (∼0.25 eV) to lower binding energies, suggesting that amorphous Ni-Co complexes were the main cause in the phase conversion of MoS2.
