Catalytic performance of binary transition metal sulfide FeCoS2/rGO for lithium–sulfur batteries.

The FeCoS₂/rGO was synthesized by a one-step hydrothermal method, which has the advantages of environmental friendliness and low cost. Dense and homogeneous FeCoS₂ nanodots are dispersed in the reduced graphene oxide flakes, which is beneficial to improve catalytic activity. Compared with FeS₂/rGO, FeCoS₂/rGO exhibits much higher initial discharge capacity and much better capacity retention ratio. The lower activation energy and the relatively narrow peak shape and small reduction/oxidation peak spacing show that FeCoS₂/rGO have better catalytic activity than FeS₂/rGO. It can be also confirmed by first-principles calculation that the adsorption energy of the Fe site (− 1.8334 eV) and the Co site (− 1.7539 eV) on the FeCoS₂ surface is better than that of FeS₂. So, the synergistic reaction of Fe and Co will adjust microregional electron density and change binding energy to polysulfides. [ABSTRACT FROM AUTHOR]