Doping-driven electronic structure and conductivity modification of nickel sulfide.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Poor electrical conductivity limits the electrochemical performance of electrode materials, hindering their theoretical capacity.
• Binary NiS2/Ni3S4 hybrid nickel sulfide exhibits potential for electrochemical applications but suffers from low conductivity.

Purpose of the Study:

• To improve the intrinsic electrical conductivity and electrochemical performance of NiS2/Ni3S4 hybrid nickel sulfide.
• To investigate the effects of transition metal doping (Co, Mn, Ag) on the electronic structure and conductivity of nickel sulfide.

Main Methods:

• Facile doping of transition metal atoms (Co, Mn, Ag) into NiS2/Ni3S4 hybrid nickel sulfide.
• Experimental characterization and density functional theory (DFT) calculations to analyze electronic structure and conductivity.
• Fabrication and testing of asymmetric supercapacitors using doped nickel sulfide and reduced graphene oxide (rGO).

Main Results:

• Doping with transition metals significantly improved the electrical conductivity of NiS2/Ni3S4 by modifying electronic structure and forming intermediate bands.
• 0.5% Co-doped NiS2/Ni3S4 achieved a highest specific capacitance of 2874 F g-1 at 1 A g-1, a 29.4% increase over non-doped material.
• Asymmetric supercapacitors using doped nickel sulfide//rGO exhibited high specific energy densities (up to 36.6 W h kg-1 at 800 W kg-1).

Conclusions:

• Transition metal doping is an effective strategy to enhance the conductivity and electrochemical properties of NiS2/Ni3S4 hybrid materials.
• The study demonstrates a pathway for fabricating high-performance pseudocapacitive electrode materials for energy storage applications.