High-Temperature Oxidized Mo₂CT MXene for a High-Performance Supercapacitor.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Molybdenum carbide (Mo2CT) MXene was considered unsuitable for supercapacitor applications.
• Developing advanced electrode materials is crucial for energy storage devices.

Purpose of the Study:

• To develop a method for fabricating a Mo2C/MoO3 heterostructure from Mo2CT MXene.
• To evaluate the supercapacitor performance of the fabricated heterostructure.

Main Methods:

• Short oxidation of Mo2CT in air at moderately high temperatures to form Mo2C/MoO3 heterostructure.
• Characterization of material stability and phase transitions.
• Electrochemical testing of electrode performance in aqueous and solid-state systems.

Main Results:

• Mo2CT MXene exhibits stability in air up to 700 °C.
• The Mo2C/MoO3 heterostructure reduces the H+ diffusion energy barrier.
• An aqueous electrode achieved a capacitance of 811 F g-1.
• A symmetric solid-state supercapacitor delivered 224 F g-1 with 91.05% retention after 7500 cycles.
• The supercapacitor demonstrated good low-temperature performance down to -60 °C.

Conclusions:

• The proposed oxidation method successfully transforms Mo2CT MXene into a high-performance supercapacitor electrode.
• The Mo2C/MoO3 heterostructure offers a promising pathway for advanced energy storage solutions.
• This work highlights the potential of previously overlooked MXene materials for supercapacitors.