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

A novel type of phosphorus doped TiCT MXene nanosheets (P-TiCT) is synthesized via a facile and controllable strategy of annealing MXene nanosheets with the presence of sodium hypophosphite. A combination of theoretical density functional theory calculation and experimental X-ray photoelectron spectroscopy discloses that the doped P atoms are prone to fill into Ti vacancies first due to their lowest formation free energy (ΔG = -0.028 eV·Å) and next to bond with surface terminals on MXene layers (ΔG = 0.