Role of defects on the electrochemical performance of MnS nanoparticles decorated 2H-MoS₂ nanoflower: Experimental and theoretical investigation

We report the influence of MnS nanoparticles on the surface morphological, structural, chemical, and electrochemical performance of 2H-MoS₂ nanoflower (MoS₂/MnS) produced by a facile hydrothermal method. Morphological study reveals that the incorporation of MnS nanoparticles distorts the lattice fringe and increases the interlayer spacing of the MoS₂ nanoflower. XPS analysis reveals a partial conversion from the 2H-MoS₂ to 1T- MoS₂ together with the formation of defects states in the nanoflower due to the sulfur vacancies created by MnS. The MoS₂/MnS nanocomposite provides improved electrochemical performance with a maximum specific capacitance of 351 Fg⁻¹ at a current density of 0.3 Ag⁻¹ and a capacitive retention of 80 % after 8000 charging/discharging cycles. The density functional theory (DFT) revealed defect states formed in forbidden energy regions because of strong hybridization between Mo-d and Mn-d orbitals. The improved electrochemical performance of the MoS₂/MnS nanocomposite can be attributed to the defect rich 1T-MoS₂ phase, the enlarged surface, and increased interlayer spacing originating from the decoration of MnS nanoparticles. The combined experimental and theoretical approach, together with a facile synthesis technique, will open up an economical route for the fabrication of efficient energy storage devices.