Axial π─Bond Tuning of Anchored FeN ₄ for Electrocatalytic Oxygen Reduction

ABSTRACT The curvature change of the support can control the induced local stress strain and directly change the properties and performance of the layered materials. Herein, we successfully in situ grew graphdiyne (GDY) on the surface of carbon nanotubes (CNTs) to form a heterojunction material with curved structure and highly surface‐active. Our results indicated that the surface‐grown GDY can deform into a curved‐GDY (cGDY) due to internal stress. Such structural rearrangement regulates the charge distribution on interface of graphdiyne/CNTs and increases the charge density of C sp ─C sp bonds within bent diacetylene linkages (−C sp ≡ C sp −C sp ≡C sp −). While loading iron phthalocyanine (FePc) to this bent surface, the interactions and the interfacial repulsive force in the system were greatly enhanced, resulting in the elevated energy level of Fe 3d z 2, which was beneficial to the adsorption of O 2 , and the hybridization between Fe (3d xz , 3d yz , and 3d z 2) and *OO (2p x , 2p y , and 2p z ) orbitals, significantly enhancing activation of O 2 . Therefore, compared with the FeN 4 moiety on pure CNTs or GDY, this heterojunction structure through axial π ─ bond tuning demonstrates superior performance with a half‐wave potential of 0.905 V and a Tafel slope of 31.7 mV dec −1 .