High-Density Asymmetric Iron Dual-Atom Sites for Efficient and Ultra-Stable Electrochemical Water Oxidation

Abstract Double-atom catalysts (DACs) have open up novel paradigms in the field of rapidly developing atomic catalysis because of their great potential to promote catalytic performances in various reaction systems. However, increasing the loading and extending the service life of metal active centers represents a grand challenge for the efficient utilization of DACs. Here, we rationally design asymmetric nitrogen, sulfur-coordinated diatomic iron centers on highly defective nitrogen-doped carbon nanosheets (denoted as A-Fe₂S₁N₅/SNC, A: asymmetric), which possesses the atomic configuration of N₂S₁Fe-FeN₃ moiety. The abundant defects and low-electronegativity heteroatoms in the carbon-based framework endow the A-Fe₂S₁N₅/SNC with a high loading of 6.72 wt%. Furthermore, the A-Fe₂S₁N₅/SNC demonstrates an ultra-low overpotential of 193 mV for the oxygen evolution reaction (OER) at 10 mA cm⁻ ², outperforming the commercial RuO₂ catalysts. In addition, the A-Fe₂S₁N₅/SNC exhibits extraordinary stability, maintaining > 97% activity for over 2000 hours during the OER process. This work provides a practical scheme for simultaneously balancing activity and stability of DACs toward electrocatalysis applications.