Sublimation Transformation Synthesis of Dual‐Atom Fe Catalysts for Efficient Oxygen Reduction Reaction

Abstract Dual‐atom catalysts (DACs) have garnered significant interest due to their remarkable catalytic reactivity. However, achieving atomically precise control in the fabrication of DACs remains a major challenge. Herein, we developed a straightforward and direct sublimation transformation synthesis strategy for dual‐atom Fe catalysts (Fe 2 /NC) by utilizing in situ generated Fe 2 Cl 6 (g) dimers from FeCl 3 (s). The structure of Fe 2 /NC was investigated by aberration‐corrected transmission electron microscopy and X‐ray absorption fine structure (XAFS) spectroscopy. As‐obtained Fe 2 /NC, with a Fe−Fe distance of 0.3 nm inherited from Fe 2 Cl 6 , displayed superior oxygen reduction performance with a half‐wave potential of 0.90 V (vs. RHE), surpassing commercial Pt/C catalysts, Fe single‐atom catalyst (Fe 1 /NC), and its counterpart with a common and shorter Fe−Fe distance of ~0.25 nm (Fe 2 /NC‐S). Density functional theory (DFT) calculations and microkinetic analysis revealed the extended Fe−Fe distance in Fe 2 /NC is crucial for the O 2 adsorption on catalytic sites and facilitating the subsequent protonation process, thereby boosting catalytic performance. This work not only introduces a new approach for fabricating atomically precise DACs, but also offers a deeper understanding of the intermetallic distance effect on dual‐site catalysis.