Atomically Dispersed Fe–N3C Sites Induce Asymmetric Electron Structures to Afford Superior Oxygen Reduction Activity. Issue 22 (7th May 2022) - Tong, Miaomiao
Abstract: Introducing heteroatoms into atomically dispersed Fe–N4 sites with symmetric electron distribution can adjust the imperfect oxygenated adsorption‐activation and promote oxygen reduction reaction (ORR) activity. However, the relevant design synthesis and deeply understanding the electrocatalytic mechanism of such an asymmetric structure by introducing Fe–C coordination remains challenging. Herein, the structural stability of Fe–N x C y ( x = 0 ≈ 4, y = 4– x ) is first theoretically predicted and indicates that the energy of Fe–N4 in the two most stable structures is greater than that of Fe–N3 C. Subsequently, Fe–N4 and Fe–N3 C configurations are controlled synthesized by adjusting pyrolytic temperature. The Fe–N3 C‐based electrocatalyst displays a boosted ORR activity with a half‐wave potential of 0.91 V and superior long‐term stability, outperforming Fe–N4, Pt/C, and state‐of‐the‐art noble metal‐free electrocatalysts. Density functional theory calculations unveil that Fe–N3 C is much more favorable for electron delocalization than Fe–N4 . Furthermore, the residual Zn atom derived from ZIF‐8 would give its d‐orbit electron to the Fe atom, so the synergy between Fe–N3 C and Zn–N4 makes an enhanced ORR activity. Abstract : Atomically dispersed asymmetric Fe–N4 and symmetric Fe–N3 C configurations are respectively controllably constructed based on density functional theory results. The Fe in Fe–N3 C is much more beneficial to electron delocalization, which could promote adsorption activation of oxygen‐containing intermediates and oxygen reduction reaction activity.