A Simple and Expeditious Route to Phosphate-Functionalized, Water-Processable Graphene for Capacitive Energy Storage

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Phosphate-functionalized carbon nanomaterials are crucial for advanced electrochemical energy storage.
• Developing efficient and sustainable synthesis methods for these materials is an ongoing challenge.

Purpose of the Study:

• To report a simple, high-yield method for producing phosphate-functionalized graphene (PFG) via anodic exfoliation.
• To investigate the effects of electrolyte concentration on graphite exfoliation and functionalization.
• To evaluate the electrochemical performance of PFG as an electrode material for energy storage.

Main Methods:

• Anodic exfoliation of graphite foil using aqueous solutions of phosphoric acid (H3PO4) or sodium phosphate (Na3PO4) at room temperature.
• Optimization of electrolyte concentrations (0.25 M H3PO4 and 0.05 M Na3PO4) for efficient exfoliation and functionalization.
• Characterization of PFG using phosphorus content analysis and electrochemical testing in three-electrode and symmetric cell configurations.

Main Results:

• Optimal concentrations yielded PFG with high phosphorus content (2.2 at.% for acid, 1.4 at.% for salt).
• PFG electrodes demonstrated competitive capacitive performance: ~375 F/g (acid) and 356 F/g (salt).
• Symmetric devices exhibited high energy/power densities (up to 17.6 Wh/kg and 10,200 W/kg) with excellent capacitance retention (>98% after 10,000 cycles).

Conclusions:

• The proposed anodic exfoliation method is a simple, high-yield, and sustainable approach for producing PFG.
• PFG exhibits excellent electrochemical performance, making it suitable for high-performance energy storage applications.
• The methodology supports a circular-synthesis process, contributing to greener energy storage solutions.