Regulation of d‐Orbital Electron in Fe‐N4 by High‐Entropy Atomic Clusters for Highly Active and Durable Oxygen Reduction Reaction

• Published in: Advanced functional materials 2024-11, Vol.34 (46), p.n/a
• Main Authors: Yang, Gege, Cai, Hairui, Zhang, Nan, Wang, Bin, Liang, Chao, Zhang, Shengli, Yang, Zhimao, Yang, Shengchun
• Format: Article
• Language: English
• Subjects: Adsorption; Aqueous solutions; Atomic clusters; Catalysts; Chemical reduction; Configurations; Desorption; Diffusion barriers; Diffusion rate; Durability; d‐Orbital Electron Modulation; Electronic structure; Entropy; Entropy of activation; Fe single atom; high‐entropy atomic clusters; Iron; Orbital stability; oxygen reduction reaction; Oxygen reduction reactions; Pyrolysis; Structural stability; Synergistic effect
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202407775

Simultaneously improving activity and stability is a crucial yet challenge in the development of metallic single‐atom‐based catalysts. In current work, a novel approach is introduced to address this issue by combining post‐adsorption and secondary pyrolysis techniques to create a synergistic catalytic system, in which the single atoms (SAs) Fe sites played in the NC matrix (Fe─NC) are coupled with high‐entropy atomic clusters (HEACs). Theoretical calculations reveal that the incorporation of HEACs lead to a rehybridization of the 3d orbital configuration of Fe‐N4, which helps to balance the adsorption/desorption energy of oxygenated intermediates. In situ spectroscopy further reveals that the rate‐limiting step of OH* desorption on HEAC/Fe─NC in oxygen reduction reaction (ORR) is more facile compared to atomic Fe─NC, implying a higher ORR activity. Moreover, the synergistic effect of diffusion activation barriers and configuration entropy contributes to the structural stability of HEAC/Fe─NC, resulting in remarkable durability. Consequently, this unique catalyst exhibits half‐wave potentials of 0.927 and 0.828 V in an aqueous solution of KOH (0.1 m) and HClO4 (0.1 m), respectively, along with excellent durability. The findings propose a novel strategy for modulating the electronic structure of metallic SAs catalysts and enhancing their stability through strong interactions between SAs and HEACs. The incorporation of HEACs leads to a rehybridization of the 3d orbital configuration of Fe‐N4 and results in an increased occupation of an antibonding state when Fe center adsorbs OH*, which helps to balance the energy associated with the adsorption/desorption of oxygenated intermediates. Moreover, the synergistic effect of diffusion activation barriers and configuration entropy contributes to the structural stability of HEAC/Fe─NC, resulting in remarkable electrocatalytic durability.