Electroactive FeS2-modified MoS2 nanosheet for high-performance supercapacitor

Electroactive FeS2-modified MoS2 (FeS2/MoS2) nanosheet grown on Mo foil is designed as supercapacitor electrode material. FeS2/MoS(2 )nanosheet is crosslinked to form nanoporous microstructure. Density functional theory calculation reveals FeS2/MoS2 exhibits much narrowed bandgap and high density of states at the Fermi level, suggesting highly improved conductivity. The charge transfers resistance decreases from 1.375 Omega of MoS2 to 0.4167 Omega of FeS2/MoS2. FeS2/MoS(2 )exhibits higher specific capacity (495 and 394 mF cm(-2)) than MoS2 (132 and 218.1 mF cm(-2)) and FeS2 (315 and 286.5 mF cm(-2)) at 1.0 mA cm(-2) in 3.0 M KOH and 0.5 M Na2SO4. The rate capacity retention is enhanced from 57.8% of MoS2 and 73.3% of FeS2 to 76.14% of FeS2/MoS2 in 0.5 M Na2SO4 when current density increases from 1 to 10 mA cm(-2), indicating its improved rate capability. The cycling capacity retention keeps 100.2% of MoS2 and 100.7% of FeS2/MoS(2 )for 5000 cycles at 5 mA cm(-2) in 0.5 M Na2SO4, indicating the similar cycling stability. An asymmetric solid-state supercapacitor using FeS2/MoS2 anode, exfoliated graphite carbon paper cathode and NaMoO4-Na2SO4-PVA gel electrolyte achieves specific capacity of 1.88 F cm(-3) (112.8 mF cm(-2)) at 1.0 mA cm(-2), energy density of 0.936 mWh cm(-3) (56.56 mWh cm(-2)), capacity retention of 97.8% after 5000 cycles at 5.0 mA cm(-2) and 1.9 V output voltage. (C) 2020 Elsevier B.V. All rights reserved.