Dynamic D-p-π Orbital Coupling of FeN4-Spπ Atomic Centers on Graphitized Carbon Toward Invigorated Sulfur Kinetic Chemistry

Abstract

Precisely modulating d-p orbital coupling of single-atom electrocatalysts for sulfur reduction reactions in lithium-sulfur batteries maintains tremendous challenges. Herein, a dynamic d-p-π orbital coupling modulation is elucidated by unsaturated Fe centers on nitrogen-doped graphitized carbon (NG) coordinated with trithiocyanuric acid featuring with p-π conjugation to engineer Fe single atom architecture (Fe_N4-S_pπ-NG). Intriguingly, this coordination microenvironment of the Fe center is dynamically reconstituted during charge/discharge processes, because of the formation of trilithium salts rooted from the departed axial ligands to engineer interfacial coating on the sulfur cathode, and then it recovers to the initial coordination configuration. Theoretical and experimental results unravel that the axial p-π conjugated ligand reinforcing d-p orbital coupling enables the interfacial charge interaction, thereby strengthening LiPSs adsorption, and reducing the Li₂S decomposition barrier by formation of Fe─S and S─Li bonds. Thus, dynamic d-p-π orbital coupling modulation of Fe_N4-S_pπ endow lithium-sulfur batteries with considerable electrochemical performances, highlighting an intriguingly dynamic orbital coupling modulation strategy for single atom electrocatalysts.