Engineering p–d Coupling at Fe–Bi and Zn–Bi Sites for Efficient Li–S Conversion

Electrocatalytic sulfur hosts are crucial for high-performance, lightweight lithium-sulfur (Li-S) batteries, demanding atomically dispersed metals with precisely tuned electronic structures. Here, we present 3d-6p dual-atom catalysts (DACs) composed of earth-abundant Fe-Bi or Zn-Bi pairs anchored on nitrogen-doped carbon. Aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy confirm atomically dispersed bimetallic centers stabilized through TM-N coordination. In Li-S cells, DACs, particularly Fe-Bi, markedly accelerate polysulfide conversion, achieving near-ideal discharge plateau ratios, superior rate capability with >50% capacity retention at 3C, and about 80% retention after 1000 cycles at 1C. Density functional theory indicates that Bi induces strong ligand-field and p-d coupling effects, shifting Fe 3d states toward the Fermi level and polarizing Zn through charge redistribution. This Bi-driven cooperative activation transcends d-electron limitations, offering a general and scalable route to high-rate, durable Li-S electrocatalysts.