Structural analyses and deposition of purified carbon nanotubes using electrophoretic deposition

This study was conducted to elucidate the analysis of purified carbon nanotubes (CNTs) in dimethylformamide (DMF) that allows good performance in electrophoretic deposition (EPD) process. In this attempt, the effect of mild acid treatment of nitric acid (HNO₃) on CNTs of purification process was evaluated. The purified CNTs quality was observed using Thermal Gravimetric Analysis (TGA), Fourier Transformation Infrared Spectroscopy (FTIR), Transmission Electron microscopy (TEM), Scanning Electron Microscope (SEM) and Energy Dispersive x-ray (EDX). Meanwhile for the suspended purified CNTs, the conducted analyses were zeta potential and UV–vis spectroscopy in different solvents (DMF, distilled water, mixture of acetone/ethanol, NMP, and Texanol). The suspension stability was observed for three days prior to EPD process. It was found that the purity of CNTs increased where only 0.03 wt.% of catalyst were left from TGA analyses. Moreover, the TEM and SEM images showed that the catalyst was being removed after purification and functional groups are introduced as observed through FTIR analysis. The UV–vis results showed that the CNTs were suspended longer in DMF and formed more stable suspension as compared to other solvents where constant reading during observations were obtained while the zeta potential result was indicated to have sufficient particle charge (−35.87 mV) for EPD process. In addition, the mechanism of CNTs purifications was studied and it clearly justified the role of functional group as CNTs charge with good reading of zeta potential was obtained. The SEM image of EPD result shows the performance of CNTs suspension in DMF with optimum deposition thickness of 11.98 μm and 0.9 mg of deposition weight. (paper)