Interaction between NiOx and MWСNT in NiOx/MWСNTs composite: XANES and XPS study

The current work presents the investigation of the interaction between NiOx and multi-walled carbon nanotube (MWCNTs) sidewall in NiOx/MWCNT nanocomposite, synthesized by electrochemical metal oxidation and dispersion method using the near edge X-ray absorption fine structure (XANES) and X-ray photoelectron spectroscopies. Scanning electron microscopy (SEM) illustrated that formation of the NiOx/MWCNT composite leads to decreasing of the NiOx sheets size and their dispersion among nanotubes. Comparison of the C K-edge XANES spectra of the initial high-purified MWCNTs with NiOx/MWCNTs indicates significant shape changes of the nanocomposite spectrum. Changes in π resonance and inter-resonance region of C K-edge XANES spectrum showed the appearance of new chemical bonds in the carbon nanotubes as result of formation of NiOx/MWCNTs nanocomposite, associated with partial chemical interaction of NiOx with CNT walls. The chemical state of Ni in the composite compound is 2+ and there is Ni with different oxygen surroundings in the NiOx/MWCNT nanocomposite.