Authors: Yunkun Dai, Bo Liu, Ziyu Zhang, Pan Guo, Chang Liu, Yunlong Zhang, Lei Zhao, Zhenbo Wang
Published: 2023-02-11
Source: Full article
AbstractRegulating the electronic states of single atomic sites around the Fermi level remains a major concern for boosting the electrocatalytic oxygen reduction reaction (ORR). Herein, a Fe d‐orbital splitting manner modulation strategy by constructing axial coordination on FeN4 sites is presented. Experimental investigations and theoretical calculations reveal that the axial tractions induce the distortion of square‐planar field (FeN4 SP), up to the quasi‐octahedral coordination (FeN4O1 OCquasi), thus leading to the electron rearrangement with a diluted spin polarization. The declined population of unpaired electrons in dz2, dxz and dyz states engenders a moderate adsorption of ORR intermediates, thereby reinforcing the intrinsic reaction activity. In situ infrared spectroscopy further demonstrates that the reordering of d‐orbital splitting and occupation facilitates the desorption of *OH. The FeN4O1 OCquasi exhibits a dramatic improvement of kinetic current density and turnover frequency, which are fivefold and tenfold higher than those of FeN4 SP. This work presents a novel understanding on improving the electrocatalytic performance through the orbital‐scale manipulation.