Atomically Dispersed Fe-N4 Modified with Precisely Located S for Highly Efficient Oxygen Reduction

• Main Authors: Yin Jia, Xuya Xiong, Danni Wang, Xinxuan Duan, Kai Sun, Yajie Li, Lirong Zheng, Wenfeng Lin, Mingdong Dong, Guoxin Zhang, Wen Liu, Xiaoming Sun
• Format: Article
• Language: English
• Published: SpringerOpen 2020-05-01
• Series: Nano-Micro Letters
• Subjects: Atomic dispersion; Iron–nitrogen moiety; Electronic structure; Sulfur doping; Oxygen reduction
• Online Access: http://link.springer.com/article/10.1007/s40820-020-00456-8

Abstract Immobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety.