N-Terminalized Ti₃ C₂ T_x MXene for Supercapacitor with Extraordinary Pseudocapacitance Performance

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• MXenes show promise for electrochemical energy storage devices like supercapacitors.
• Surface terminal groups on MXenes are crucial for pseudocapacitive mechanisms.
• Existing terminal groups (-F and -O) have limitations in ion transport and binding sites.

Purpose of the Study:

• To develop a novel MXene material with improved electrochemical energy storage properties.
• To investigate the effect of replacing fluorine terminal groups with nitrogen terminal groups on MXene performance.
• To understand the pseudocapacitive mechanism facilitated by nitrogen terminal groups.

Main Methods:

• Synthesis of nitrogen-terminated MXene (MXene-N).
• Electrochemical characterization including gravimetric capacitance measurements.
• Spectroscopic analysis and density functional theory (DFT) calculations to elucidate the mechanism.

Main Results:

• MXene-N electrodes achieved high gravimetric capacitance (566 F g^-1 at 2 mV s^-1 and 588 F g^-1 at 1 A g^-1).
• The potential window of the supercapacitors was significantly increased with MXene-N.
• Spectra analysis and DFT calculations confirmed the role of nitrogen terminal groups in enhancing performance.

Conclusions:

• Replacing fluorine terminal groups with nitrogen groups in MXenes is an effective strategy for improving supercapacitor performance.
• The novel MXene-N material offers a promising pathway for advanced electrochemical energy storage.
• Terminal group modulation is a key factor in optimizing MXene properties for energy applications.