Charge‐transfer‐regulated bimetal ferrocene‐based organic frameworks for promoting electrocatalytic oxygen evolution

• Published in: Carbon energy Vol. 5; no. 6
• Main Authors: Hu, Jinsong, Xu, Qiaoling, Wang, Xiaoyu, Huang, Xinhua, Zhou, Chunhui, Ye, Ying, Zhang, Lei, Pang, Huan
• Format: Journal Article
• Language: English
• Published: Wiley 01-06-2023
• Subjects: density functional theory simulations; electronic structure regulation; hierarchical structure; metal–organic frameworks; oxygen evolution reaction
• ISSN: 2637-9368; 2637-9368
• DOI: 10.1002/cey2.315

The ferrocene (Fc)‐based metal–organic frameworks (MOFs) are regarded as compelling platforms for the construction of efficient and robust oxygen evolution reaction (OER) electrocatalysts due to their superior conductivity and flexible electronic structure. Herein, density functional theory simulations were addressed to predict the electronic structure regulations of CoFc‐MOF by nickel doping, which demonstrated that the well‐proposed CoNiFc‐MOFs delivered a small energy barrier, promoted conductivity, and well‐regulated d‐band center. Inspired by these, a series of sea‐urchin‐like CoNiFc‐MOFs were successfully synthesized via a facile solvothermal method. Moreover, the synchrotron X‐ray and X‐ray photoelectron spectroscopy measurements manifested that the introduction of nickel could tailor the electronic structure of the catalyst and induce the directional transfer of electrons, thus optimizing the rate‐determining step of *O → *OOH during the OER process and yielding decent overpotentials of 209 and 252 mV at 10 and 200 mA cm−2, respectively, with a small Tafel slope of 39 mV dec−1. This work presents a new paradigm for developing highly efficient and durable MOF‐based electrocatalysts for OER.
Density functional theory simulations confirm that Ni doping can effectively tune the electronic structure of CoFc‐MOF and optimize its d‐band centers. ΔG calculations further reveal that Ni doping reduces the energy barrier of the rate‐determining step *O → *OOH. The ultimate CoNiFc‐MOF exhibits outstanding electrocatalytic oxygen evolution activity with decent overpotentials of 209 and 252 mV at 10 and 200 mA cm−2 in alkaline electrolytes.