Phosphorus doped molybdenum disulfide regulated by sodium chloride for advanced supercapacitor electrodes

As a pseudocapacitor electrode material, molybdenum disulfide (MoS₂) usually shows inferior capacity, rate capability and cyclability. Structural regulation and heteroatom doping are the available methods to ameliorate the electrochemical properties of MoS₂. Herein, phosphorus doped molybdenum disulfide regulated by sodium chloride (SP-MoS₂) is successfully synthesized using phosphomolybdate acid as a molybdenum source and an in situ dopant and sodium chloride (NaCl) as a structural regulator. Under the structural regulation of NaCl, the SP-MoS₂ nanosheets exhibit an interweaved architecture with a large interlayer spacing of 0.68 nm. Owing to the in situ P doping and large specific surface area (21.0 m² g^-1), the SP-MoS₂ electrode possesses a maximum capacity of 564.8 F g^-1 at 1 A g^-1 and retains 56.3% of the original capacity at 20 A g^-1. Density functional theory (DFT) calculations indicate that SP-MoS₂ displays a high K⁺ average adsorption energy of -3.636 eV. In addition, the fabricated SP-MoS₂//AC asymmetric supercapacitor device displays an energy density of 22.8 W h kg^-1 at 759 W kg^-1.