Iron-Based Metal-Organic Framework System as an Efficient Bifunctional Electrocatalyst for Oxygen Evolution and Hydrogen Evolution Reactions

Minli Gu; Shi-Cheng Wang; Chen Chen; Dengke Xiong; Fei-Yan Yi

doi:10.1021/acs.inorgchem.0c00100

Iron-Based Metal-Organic Framework System as an Efficient Bifunctional Electrocatalyst for Oxygen Evolution and Hydrogen Evolution Reactions

Inorg Chem. 2020 May 4;59(9):6078-6086. doi: 10.1021/acs.inorgchem.0c00100. Epub 2020 Apr 20.

Authors

Minli Gu¹, Shi-Cheng Wang¹, Chen Chen¹, Dengke Xiong¹, Fei-Yan Yi^{1

2

3}

Affiliations

¹ School of Materials Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, P. R. China.
² State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, Jilin 130022, P. R. China.
³ Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province, Ningbo, Zhejiang 315211, P. R. China.

PMID: 32310645
DOI: 10.1021/acs.inorgchem.0c00100

Abstract

The fabrication of highly efficient and sustainable electrocatalysts used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is exceedingly challenging and warranted for overall water splitting. In this work, we successfully synthesized a series of metal-organic frameworks (MOFs), namely, as Fe₂M-MOF (M = Fe, Co, Ni, Zn, Mn; H₄L = 3,3,5,5'-azoxybenzenetetracarboxylic acid) under a simple and mild condition, in which the Fe₃ cluster as a basic building unit was replaced by the second kind of metal center; at the same time, a redox-active organic linker was adopted. The Fe₂M-MOF system as a multifunctional catalyst realizes great improvement of the OER and HER performances. Among of them, the Fe₂Co-MOF catalyst exhibits an extremely low overpotential of 339 mV at a current density of 10 mA cm^-2 and a very small Tafel slope of 36.2 mV dec^-1 in an alkaline electrolyte for OER. This result has far exceeded the commercial catalyst IrO₂. Meanwhile, Fe₂Zn-MOF manifests excellent HER activity with a small overpotential of 221 mV at 10 mA cm^-2 and a low Tafel slope of 174 mV dec^-1. In addition, the good long-term stability for these catalysts can be evaluated under working conditions. Systematic investigations are used to explain the enhanced electrocatalytic mechanism. In conclusion, we provide a simple and effective strategy for the preparation of multifunctional catalysts for energy conversion applications based on a pristine MOF material with redox-active metal centers and organic linkers.