Adsorption-catalysis mechanism of non-noble single transition metal atom immobilized on Mo₂CS₂ MXene as sulfur hosts for Lithium−Sulfur batteries

Lithium-sulfur (Li-S) batteries have emerged as a leading contender for next-generation energy storage systems, owing to their exceptional theoretical specific energy and cost-effectiveness. However, persistent challenges including the lithium polysulfides (LiPSs) shuttle effect and sluggish redox kinetics continue to hinder their practical implementation. To address these challenges, developing multifunctional sulfur hosts capable of concurrently confining and catalyzing LiPSs represents a critical research direction. This study proposes a novel class of single-atom catalysts (SACs) through atomic dispersion of transition metals (TM = Fe, Co, Ni, Cu) on Mo₂CS₂ MXene substrates (denoted as TM/SACs), systematically evaluated through density functional theory (DFT) calculations. First-principles analyses reveal that all TM/SAC configurations inherently maintain metallic conductivity, ensuring efficient electron transport throughout the charge-discharge cycle. The engineered TM sites demonstrate dual functionality: (1) strong chemisorption of LiPSs via TM-S covalent bonding, effectively suppressing polysulfide migration, and (2) catalytic activation of sulfur species with a low energy barrier. A developed binding energy-based descriptor (E_b(S)) effectively characterizes both anchoring and catalytic functionalities of TM/SACs, with 2.55–4.59 eV identified as the optimal range for superior sulfur host performance. This comprehensive theoretical framework establishes fundamental design principles and provides critical guidance for engineering high-performance MXene-based sulfur host architectures. © 2025 Elsevier B.V.