Engineering Anion p-Band Centers in Mo-Based Compounds for Tunable LiPSs Adsorption-Catalysis

The shuttle effect and sluggish redox kinetics severely hinder the performance of lithium–sulfur (Li–S) batteries. Herein, a series of molybdenum-based compounds (Mo2C, Mo2N, MoO2, MoP, and MoS2) anchored on nitrogen-doped carbon (NC) hollow spheres are rationally designed and fabricated, while the influence of nonmetallic anions on the electronic structure of molybdenum based compounds and adsorption-catalytic conversion behavior of polysulfides (LiPSs) were systematically studied. By employing identical NC hollow spheres as the substrate to eliminate influence of morphological and substrate, the intrinsic electronic influence of anionic coordination in MoaXb compounds (X = C, N, O, P, S) can be independently assessed. Electrochemical analyses including Li2S nucleation, CV, GITT, and in situ EIS-DRT demonstrate that the selection of anions can effectively regulate the electronic structure of Mo through d-p orbital hybridization and further govern the LiPSs adsorption, Li2S nucleation, charge transfer, and Li+ diffusion. Among all samples, MoP/NC delivers the best adsorption and catalysis bifunctional performance, due to moderate LiPSs binding energy, low polarization, and strong d–p orbital hybridization. Density functional theory (DFT) calculations reveal that redox kinetics are governed by d–p orbital hybridization and band center alignment. This study provides fundamental insight into anion coordinated electronic structure engineering, offering design principles for advanced sulfur hosts with strong adsorption and catalytic capabilities.