Catalysis unleashed: Tuning the d-band center of Mo for efficient sodium polysulfide transformation

Abstract

Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur (RT Na-S) battery catalysts. Herein, we systematically investigate Fe-, Co-, and Ni-incorporated Mo₂C as catalysts for RT Na-S battery to elucidate the intrinsic correlation between the d band center of Mo in Mo₂C and its catalytic activity. Combining experimental and theoretical analysis revealed that Ni-substituted Mo₂C elevates the d band center while significantly reducing antibonding orbitals (π*) occupancy compared to Fe-substituted Mo₂C and Co-substituted Mo₂C counterparts. This electronic restruction enhances d-p hybridization at the Mo-S interface, which strengthens sodium polysulfides adsorption energy and enhances charge transfer, thereby steering sulfur redox pathways toward thermodynamically favorable configurations. Our findings elucidate the intricate interplay between the electronic structure and catalytic activity of Mo₂C, advancing a novel perspective for the rational design of RT Na-S battery catalysts through tailored modulation of antibonding orbital occupancy.