Engineering of single atomic Fe-N4 sites on hollow carbon cages to achieve highly reversible MoS2 anodes for Li-ion batteries.

[Display omitted] • Single atom catalyst with Fe-N 4 sites anchored on hollow carbon cage is synthesized. • Hollow carbon cage structure facilitates exposure of the active Fe-N 4 sites. • Synergistic effect of Fe-N 4 site and hollow carbon cage improves reversibility of MoS 2 anode. • Fe- N -HCN can effectively adsorb and catalyze the rapid decomposition of Li 2 S. • The MoS 2 /Fe- N -HCN anode exhibit superior electrochemical performance. Although the single atom electrocatalysts have been demonstrated as efficient catalysts for promoting Li 2 S/Na 2 S formation and decomposition in Li-S/Na-S batteries, the functional morphological and structural engineering capable of exposing more active sites is regarded as an essential factor to further enhance the catalytic activity. Here, we have synthesized a single atomically dispersed Fe sites embedded within hollow nitrogen doped carbon cages (Fe- N -HCN) using Fe 3 O 4 spheres as an oxidant and sacrificial template, which is used as a high-efficiency catalyst for boosting the reversible capacity of MoS 2 anode in lithium-ion batteries (LIBs). As expected, the electrochemical reaction of MoS 2 /Fe- N -HCN anode exhibits higher reversibility than pure MoS 2 electrodes. Moreover, density functional theory is also employed to reveal that Fe- N -HCN can be effectively adsorbed and catalyze the rapid decomposition of Li 2 S. The hollow carbon cage structure can facilitate the exposure of the active Fe-N 4 sites and favor the mass transfer during the electrochemical reactions, thus the synergistic effect of the Fe-N 4 site and the hollow carbon cage structure together improve the catalytic activity for the conversion reaction of MoS 2 anode. [ABSTRACT FROM AUTHOR]