A temperature-dependent phosphorus doping on Ti₃C₂T_x MXene for enhanced supercapacitance.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• MXene nanosheets are promising electrode materials for energy storage.
• Optimizing MXene properties is crucial for enhancing supercapacitor performance.
• Phosphorus doping is explored as a strategy to improve MXene characteristics.

Purpose of the Study:

• To synthesize and characterize novel phosphorus-doped Ti3C2Tx MXene nanosheets (P-Ti3C2Tx).
• To investigate the mechanism of phosphorus doping in Ti3C2Tx MXene.
• To evaluate the electrochemical performance of P-Ti3C2Tx as a supercapacitor electrode material.

Main Methods:

• Synthesis of P-Ti3C2Tx via annealing MXene with sodium hypophosphite.
• Theoretical calculations using density functional theory (DFT).
• Experimental characterization using X-ray photoelectron spectroscopy (XPS).
• Electrochemical testing of supercapacitors using P-Ti3C2Tx electrodes.

Main Results:

• Phosphorus atoms preferentially occupy Ti vacancies and bond with surface terminals, forming P-C and P-O species.
• P-Ti3C2Tx electrodes exhibit a high specific capacitance of 320 F·g−1 at 0.5 A·g−1.
• Achieved excellent rate capability (83.8% capacitance retention at 30 A·g−1) and cycling stability (5000 cycles).

Conclusions:

• Phosphorus doping significantly enhances the electrochemical performance of Ti3C2Tx MXene for supercapacitors.
• The doping strategy provides a new avenue for developing high-performance MXene-based energy storage devices.
• P-Ti3C2Tx demonstrates superior capacitance, rate retention, and stability compared to undoped MXene.