Surface oxidation of carbon nanofibres

Area of Science:

• Materials Science
• Surface Chemistry

Background:

• Carbon nanofibers (CNFs) are advanced materials with diverse applications.
• Surface functionalization is crucial for tailoring CNF properties, such as wettability and reactivity.
• Understanding the impact of oxidation methods on CNF structure and surface chemistry is essential.

Purpose of the Study:

• To investigate the effectiveness of various surface oxidation methods on fishbone and parallel type carbon nanofibers.
• To characterize the resulting oxygen-containing surface groups and their impact on fiber properties.
• To compare the surface reactivity and structural integrity of different CNF types after oxidation.

Main Methods:

• Surface oxidation of carbon nanofibers using multiple methods, including a mixture of concentrated nitric and sulfuric acids.
• Characterization techniques: Infrared (IR) spectroscopy, Thermogravimetric Analysis (TGA), and X-ray Photoelectron Spectroscopy (XPS).

Main Results:

• Oxidation with concentrated HNO(3)/H(2)SO(4) was the most effective for introducing oxygen-containing surface groups.
• Formation of carboxy, carboxyic anhydride, and ether-type oxygen groups was observed, particularly at defect sites.
• Both fishbone and parallel CNFs exhibited similar surface reactivity due to defects.
• Parallel CNFs showed significant macroscopic structural changes after acid treatment, unlike fishbone CNFs.
• HNO(3)/H(2)SO(4)-treated CNFs demonstrated significantly enhanced wettability by water.

Conclusions:

• The combined nitric and sulfuric acid treatment is a highly effective method for surface oxidation of carbon nanofibers.
• Surface oxidation introduces various oxygen functionalities, enhancing CNF wettability.
• Defect sites play a critical role in the surface reactivity and oxidation process of CNFs.
• Differential structural responses between fishbone and parallel CNFs to acid treatment warrant further investigation for specific applications.