Regulating Electronic Structure of Bimetallic NiFe-THQ Conductive Metal-Organic Frameworks to Boost Catalytic Activity for Oxygen Evolution Reaction

Recently, conductive metal-organic frameworks (c-MOFs) have drawn tremendous attention for the application in oxygen evolution reaction (OER) due to their superior conductivity and highly accessible active sites. Herein, a facile method is reported to prepare a series of bimetallic c-MOFs (NixFe1-x-THQ, THQ = tetrahydroxy-1,4-benzoquinone hydrate) by using the smallest benzene-based ligand with high-density catalytic active sites for OER. By adjusting the ratio of Ni/Fe, a series of catalysts with optimal electronic structures and adsorption capacity to intermediates, and faster charge transport are obtained. Among them, Ni0.5Fe0.5-THQ exhibits superior catalytic performances for OER with a low overpotential of 272 mV at 10 mA cm-2, a small Tafel slope of 47.9 mV, and robust operation for 40 h with no detectable activity decay, which is far superior to commercial RuO2, most of traditional MOFs and even some monometallic conductive MOFs. Moreover, both the measured and simulated results manifest that Ni0.5Fe0.5-THQ can tailor the d-band center, and induce the directional transfer of electrons, optimizing the rate-determining step and adsorption capacity to intermediates during OER, thus exhibits superior electrochemical activity. This work not only presents a strategy to fabricate an electrocatalyst with remarkable OER performance but also promotes the development of THQ-based c-MOFs for electrocatalysis. Bimetallic c-MOFs NixFe1-x-THQ with high-density catalytic active site is used as OER catalyst. Ni0.5Fe0.5-THQ can tailor the d-band center, and induce the directional transfer of electrons, optimizing the rate-determining step and adsorption capacity to intermediates during OER, thus exhibits superior electrochemical activity with a low overpotential of 272 mV at 10 mA cm-2.image

Automated summary

Recently, conductive metal-organic frameworks (c-MOFs) have gained significant attention for their excellent conductivity and highly accessible active sites in the application of oxygen evolution reaction (OER). This study reports a method to prepare bimetallic c-MOFs with optimal electronic structures and adsorption capacity to intermediates by adjusting the ratio of Ni/Fe. The Ni0.5Fe0.5-THQ catalyst exhibits superior catalytic performances for OER, surpassing commercial RuO2, traditional MOFs, and even some monometallic conductive MOFs.