Tailoring a Transition\nMetal Dual-Atom Catalyst via\na Screening Descriptor in Li‑S Batteries

The adsorption-conversion paradigm of polysulfides during\nthe sulfur\nreduction reaction (SRR) is appealing to tackle the shuttle effect\nin Li-S batteries, especially based upon atomically dispersed electrocatalysts.\nHowever, mechanistic insights into such catalytic systems remain\nambiguous, limiting the understanding of sulfur electrochemistry and\nretarding the rational design of available catalysts. Herein, we systematically\nexplore the polysulfide adsorption-conversion essence via a geminal-atom\nmodel system to understand the catalyst roles toward an expedited\nSRR. A descriptor involving an electronic structure index (<i>I</i><sub>ES</sub>) and electron affinity index (<i>I</i><sub>EA</sub>) is proposed, considering the geometric and electronic\ndictation within a Fe/M (M: 3d-block transition metal) atomic ensemble.\nWith the aid of theoretical computation, we managed to identify the\nSRR thermodynamic/kinetic trends of Fe/M moieties. Guided by these\nfindings, we in target design a Fe/V-NC dual-atom catalyst, which\nharvests a minimum <i>I</i><sub>ES</sub> and maximum <i>I</i><sub>EA</sub>, accordingly demonstrating enhanced polysulfide\nadsorption-conversion and improved full-cell performances. Such a\nconsistency between a computational descriptor and experimental evidence\nhighlights the importance of an atomic catalyst screen and selection\nfor Li-S batteries.