Interfacial charge redistribution modulates surface electronic states through Ti-O-Fe bridges: Unlocking dz2-pz orbital hybridization for fast sulfur redox

Catalytic conversion of polysulfides is regarded as a crucial approach to overcome the chronic challenges from polysulfides shuttling and sluggish redox kinetics. Heterostructure catalysts can synergistically combine the advantages of each component with an interfacial built-in electric field (BIEF), demonstrating outstanding adsorption and catalytic effects. However, the relationship between surface electronic structure and interfacial charge redistribution remains unclear. Here, surface-oxidized MXene/α-Fe 2 O 3 (MXTiO/α-Fe 2 O 3 ) heterostructure is developed as model catalyst to clarify the enhancement mechanism of polysulfides adsorption and conversion. Theoretical and experimental analysis confirms that the modified MXene as an electron acceptor steals partial electrons from α-Fe 2 O 3 through interfacial asymmetric Ti-O-Fe bridge bonds, inducing the spontaneous charge redistribution. The electrons transfer through Ti-O-Fe channels creates electron-deficient Fe sites on the surface, which not only reduces the antibonding orbital electron occupation, leading to strengthening the d -p orbital hybridization between surface Fe and polysulfides, providing a strong sulfur affinity, but also weakens S S bonds for accelerated cleavage. The resulting catalyst enables Li-S batteries with a capacity of 538 mAh g −1 at 5.0C. This investigation establishes a fundamental correlation between interfacial electron delocalization and surface electronic configuration modulation, thereby providing a rational insight for designing advanced heterostructured electrocatalysts in high-performance energy storage/conversion applications.