Soft X-ray emission spectroscopy for the electronic state of water molecules influenced by plasma-treated multi-walled carbon nanotubes

• Published in: Physical chemistry chemical physics : PCCP 2021-05, Vol.23 (17), p.1468-1474
• Main Authors: Sakakibara, Noritaka, Inoue, Kenichi, Takahashi, Shion, Goto, Taku, Ito, Tsuyohito, Akada, Keishi, Miyawaki, Jun, Hakuta, Yukiya, Terashima, Kazuo, Harada, Yoshihisa
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Carbon; Colloiding; Electron states; Emission analysis; Emission spectroscopy; Functional groups; Hydrogen bonding; Multi wall carbon nanotubes; Plasma; Reconstruction; Soft x rays; Spectra; Spectrum analysis; Water chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d0cp05990k

In this study, soft X-ray emission spectroscopy of an aqueous colloidal dispersion of multi-walled carbon nanotubes modified via the plasma process in an aqueous solution was performed for investigating the electronic state of water molecules on the colloidal particles. In the aqueous dispersion, reconstruction of the hydrogen-bonded network was implied by the O 1s spectral changes in the 1b 1 ′ and 1b 1 ′′ peaks. Furthermore, the O 1s spectral intensity around the 3a 1 state was enhanced to an unusually broad energy range in comparison with previous studies. This unusual spectral change might be attributed to the hybridization of the electronic states of oxygen-containing functional groups on the surface of the plasma-modified multi-walled carbon nanotubes and that of the surrounding water molecules. Our observation indicates not only reconstruction of the hydrogen-bonded network in the aqueous dispersion but also a significant interaction of the electronic states between the water molecules and the plasma-modified multi-walled carbon nanotubes. Significant interactions of the electronic states between water molecules and multi-walled carbon nanotubes were found using soft X-ray emission spectroscopy.