Efficient Heterojunction Electrocatalysts for Polysulfide Conversion in Li–S Batteries via Dual-Geometric Coordination at Heterointerfaces

Constructing electrocatalysts with heterostructures has emerged as an efficient approach to cooperatively catalyze the conversion of lithium polysulfides (LiPSs) in lithium–sulfur (Li–S) batteries. However, it remains a formidable challenge to fundamentally understand the structure–activity relationship between the interfacial configuration and electrocatalytic performance, which is crucial for the rational design of electrocatalysts with heterojunctions. Herein, by leveraging molybdenum carbides (Mo x C) with tunable crystal structures as model electrocatalysts, we systematically investigated the geometric-configuration-dependent catalytic activity for LiPS conversion. Experimental analyses confirmed that the cubic MoC with octahedrally coordinated Mo atoms (Mo oct ) is easily passivated because of its robust LiPS affinity, while the hexagonal Mo 2 C with triangularly coordinated Mo atoms (Mo tri ) functions better in improving the interfacial charge transfer. Accordingly, the constructed heterointerfaces integrated with dual-geometric coordination endow MoC/Mo 2 C with moderate LiPS adsorption and favorable charge transfer kinetics to cooperatively catalyze LiPS conversion. Benefiting from these advantages, the Li–S batteries assembled with MoC/Mo 2 C demonstrate superior reversible specific capacities and cycling durability. This work highlights the critical role of interfacial geometric coordination in heterojunctions for LiPS retention and catalysis, offering a guiding approach for elevating the activity of heterojunction electrocatalysts.