The Structural, Electronic, and Magnetic Properties of Cobalt Disulfide Doped with Oxygen, Selenium, or Tellurium

The structural, electronic, and magnetic properties of cobalt disulfide (CoS2) doped with oxygen (O), selenium (Se), or tellurium (Te) were investigated based on the spin-polarized first-principles calculations. Both the lattice constant and volume for CoO0.25S1.75 were smaller while those for CoSe0.25S1.75 and CoTe0.25S1.75 were larger than the corresponding values for CoS2. Both CoS2 and CoO0.25S1.75 were quasi-half-metallic, and both CoSe0.25S1.75 and CoTe0.25S1.75 were quasi-metallic. For CoS2, CoSe0.25S1.75, and CoTe0.25S1.75, the valence band maximums (VBMs) were contributed by Co-3d(t2g) states near the X-point, and the conduction band minimums (CBMs) were contributed by S-3p states at the Γ-point. For CoO0.25S1.75, the VBM was contributed by Co-3d(t2g) states at the M-point, and the CBM was contributed by Co-3d(eg) states near the R-point. Both O–S and Te–S dimers were strongly polarized, and the Se–S dimer was slightly polarized. CoS2 and CoX0.25S1.75 (X = O, Se, or Te) were magnetic, and Co atoms favoured ferromagnetic interaction. Except quasi-HM CoO0.25S1.75, quasi-metallic CoX0.25S1.75, CoX0.0625S1.9375, CoX0.03125S1.96875, and perfect metallic CoX0.25S1.75*, CoX0.125S1.875, were expected more suitable for use in supercapacitor and electrocatalyst.