Tuning oxygen-containing functional groups of graphene for supercapacitors with high stability.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Graphene-based materials are promising for supercapacitors.
• Oxygen-containing functional groups in graphene influence performance.
• Controlling these groups is key to optimizing supercapacitor stability.

Purpose of the Study:

• To investigate the impact of oxygen-containing functional groups on supercapacitor stability.
• To correlate the reduction time of graphene oxide (GO) with functional group content and supercapacitor performance.
• To develop high-quality graphene for practical supercapacitor applications.

Main Methods:

• Reduced graphene oxide (rGO) was synthesized by varying hydrazine reduction time of GO.
• Material characterization using Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS).
• Supercapacitive performance was evaluated through electrochemical tests, including floating tests at elevated temperature and voltage.

Main Results:

• Increased reduction time restored the sp² structure, improved crystallinity, and removed oxygen-containing functional groups.
• Oxygenic functional groups contribute to pseudocapacitance and specific capacitance but reduce rate performance and durability.
• Optimized reduction (24 h) yielded rGO with excellent stability (60 days at 3.0 V, 45 °C).

Conclusions:

• The content of oxygen-containing functional groups in rGO significantly affects supercapacitor performance and stability.
• Removing these groups by optimizing reduction time enhances stability and rate performance.
• This research provides a pathway for producing high-quality graphene for cost-effective and practical supercapacitors.