Accurately Modulating Binuclear Metal Nodes of Metal-Organic Frameworks for Oxygen Evolution

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Controlling catalytic centers in materials is key for catalyst design.
• Metal-organic frameworks (MOFs) offer tunable metal sites for studying catalytic origins.

Purpose of the Study:

• To investigate the effect of substituting nickel with iron in Ni2-MOF nodes on catalytic activity.
• To explore the role of open metal sites (OMSs) and saturated metal sites (SMSs) in MOF catalysis.

Main Methods:

• Synthesis of Ni2-MOF and Ni1Fe1-MOF.
• Electrocatalytic testing of the oxygen evolution reaction (OER).
• Theoretical calculations to analyze electronic structure and reaction mechanisms.

Main Results:

• Ni1Fe1-MOF demonstrated superior electrocatalytic performance for OER compared to Ni2-MOF.
• Ni1Fe1-MOF exhibited an overpotential of 370 mV@10 mA cm-2 and Tafel slope of 87.06 mV dec-1.
• Theoretical calculations indicated that iron (SMS) modulates the nickel center's electronic structure, lowering the OER free energy barrier.

Conclusions:

• The strategic incorporation of iron into Ni2-MOF nodes significantly enhances OER electrocatalysis.
• Iron as a saturated metal site plays a crucial role in optimizing the electronic properties of nickel catalytic centers.
• This work provides insights into designing advanced MOF catalysts by manipulating metal site composition and coordination.