Studies on surface functionalized single wall carbon nanotube for electrochemical double layer capacitor application

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Single-wall carbon nanotubes (SWCNTs) are crucial for energy storage applications.
• Surface functionalization is key to optimizing SWCNT properties for supercapacitors.

Purpose of the Study:

• To investigate the effect of chemical and electrochemical oxidation on SWCNT surface properties.
• To correlate surface functionalization and pore structure with pseudocapacitance performance.

Main Methods:

• SWCNTs were functionalized using chemical oxidation (acid mixtures, fuming HNO3) and electrochemical oxidation (KNO2).
• Surface texture (microporous, mesoporous) and pseudocapacitance were analyzed in different electrolytes (H2SO4, Et3MeNBF4).

Main Results:

• Acid mixture treatment resulted in a microporous surface with a pseudocapacitance of 209 Fg⁻¹.
• Fuming HNO3 treatment led to a slightly non-polar surface with mesopores, yielding 202 Fg⁻¹ capacitance.
• Electrochemical oxidation with KNO2 functionalized SWCNTs with NO2 species, showing intermediate pseudocapacitance.
• Mixed acid treated SWCNTs demonstrated significant capacitance (160 Fg⁻¹) even at a high current rate of 5000 mAg⁻¹.

Conclusions:

• Surface functionalization significantly impacts SWCNT pseudocapacitance.
• Tailoring pore structure through oxidation is critical for optimizing supercapacitor performance.
• Mixed acid treated SWCNTs offer promising high-rate capacitance for energy storage devices.