Morphological modification of MWCNT functionalized with HNO3/H2SO4 mixtures

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Acidic oxidation using nitric acid/sulfuric acid mixtures is a common method for functionalizing multi-walled carbon nanotubes (MWCNTs).
• Poor control over oxidation conditions can lead to significant damage to the MWCNT structure, hindering their application potential.

Purpose of the Study:

• To investigate the impact of varying HNO3/H2SO4 ratios on the functionalization of MWCNTs.
• To understand how different ratios affect the morphological, chemical, and physicochemical properties of MWCNTs.
• To provide guidance for optimizing oxidation conditions based on specific application requirements.

Main Methods:

• Electron microscopy
• Thermogravimetric analysis
• X-ray diffraction
• Titration
• Water dispersion analysis

Main Results:

• Increasing the proportion of concentrated sulfuric acid in the HNO3/H2SO4 mixture enhances the degree of functionalization on the MWCNT surface.
• Higher sulfuric acid concentrations also lead to increased structural damage, including tube shortening and the creation of defects in the graphitic lattice.
• The ratio significantly influences the morphological and physicochemical properties of the functionalized MWCNTs.

Conclusions:

• The HNO3/H2SO4 ratio is a critical parameter for controlling the functionalization and structural integrity of MWCNTs.
• Careful adjustment of the acid mixture is necessary to balance the introduction of functional groups with the preservation of the nanotube structure.
• Findings aid in tailoring MWCNT properties for specific applications through controlled acidic oxidation.