Multi-layered thin film nanocomposite MoS2@MoO2/MWCNP/ITO-PET: Electrochemical approaches for synthesis and structural characterizations

Abstract A shell@core nanostructure of MoS2@MoO2 on multi-walled carbon nanotubes paper (MWCNP) is fabricated by a two-step electrochemical process. Consecutively, electrophoretic deposition (EPD) and galvanostatic deposition (GSD) techniques are applied to deposit MWCNP on indium tin oxide coated polyethylene terephthalate (ITO-PET) film, then, to form MoS2@MoO2 on the surface of MWCNP. Raman spectra and XRD pattern of MWCNP/ITO-PET and MoS2@MoO2/MWCNP/ITO-PET thin films confirm EPD retains the original structure of MWCNTs as well as GSD successfully generates amorphous MoS2@MoO2 as skin of MWCNP. In EPD process, MWCNT-COOH with high defect density are preferred to deposition on ITO-PET electrode as well as MoS2@MoO2 reduces defect on sidewall of MWCNTs in GSD process. The XRD patterns confirms the orthorhombic and hexagonal structure of MoO2 and MoS2, respectively. The thickness of MoS2@MoO2 skin measured on TEM images is about 13–15 nm, while the planes distance measured on HRTEM is about 3.8 A. Combination of characterization shows the mechanism leading to formation of MoS2@MoO2 nano-trail and nano-onion on body and end of MWCNTs, respectively, according defect density of the position. Thence, the two-step electrodeposition holds great potential due to its ability to rapidly produce large-area thin films as well as control nanostructures of materials.