Constructing Double Heterojunctions on 1T/2H-MoS2@Co3S4 Electrocatalysts for Regulating Li2O2 Formation in Lithium-Oxygen Batteries

Abstract

Co₃S₄ electrocatalysts with mixed valences of Co ions and excellent structural stability possess favorable oxygen evolution reaction (OER) activity, yet challenges remain in fabricating rechargeable lithium-oxygen batteries (LOBs) due to their poor OER performance, resulting from poor electrical conductivity and overly strong intermediate adsorption. In this work, fancy double heterojunctions on 1T/2H-MoS₂@Co₃S₄ (1T/2H-MCS) were constructed derived from the charge donation from Co to Mo ions, thus inducing the phase transformation of MoS₂ from 2H to 1T. The unique features of these double heterojunctions endow the 1T/2H-MCS with complementary catalysis during charging and discharging processes. It is worth noting that 1T-MoS₂@Co₃S₄ could provide fast Co–S–Mo electron transport channels to promote ORR/OER kinetics, and 2H-MoS₂@Co₃S₄ contributed to enabling moderate e_g orbital occupancy when adsorbed with oxygen-containing intermediates. On the basis, the Li₂O₂ nucleation route was changed to solution and surface dual pathways, improving reversible deposition and decomposition kinetics. As a result, 1T/2H-MCS cathodes exhibit an improved electrocatalytic performance compared with those of Co₃S₄ and MoS₂ cathodes. This innovative heterostructure design provides a reliable strategy to construct efficient transition metal sulfide catalysts by improving electrical conductivity and modulating adsorption toward oxygenated intermediates for LOBs.