Molecular Catalyst Synthesis Strategies to Prepare Atomically Dispersed Fe-N-C Heterogeneous Catalysts

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Developing efficient heterogeneous catalysts is crucial for various chemical transformations.
• Atomically dispersed metal sites on supports offer enhanced reactivity and selectivity.
• Nitrogen-doped carbon (N-C) materials are promising supports for single-atom catalysts.

Purpose of the Study:

• To present a novel strategy for integrating atomically dispersed iron within a heterogeneous nitrogen-doped carbon support.
• To mimic molecular macrocyclic iron complex synthesis for catalyst preparation.
• To enhance the catalytic activity of iron-nitrogen-carbon (Fe-N-C) materials.

Main Methods:

• Pyrolysis of ZIF-8 metal-organic framework to create N-C support.
• Solution-phase metalation of N-C support with FeCl2 and tributyl amine at 150 °C.
• Characterization using 57Fe Mössbauer spectroscopy and aberration-corrected scanning transmission electron microscopy.
• Selective removal of Zn2+ ions to increase Fe site density via transmetalation.

Main Results:

• Successful integration of atomically dispersed iron within the N-C support.
• Fe site density increased by selective Zn2+ ion removal prior to metalation.
• Demonstrated higher catalytic rates per total Fe compared to established Fe-N-C catalysts.
• Validated utility through benchmarking in an aerobic oxidation reaction.

Conclusions:

• The reported strategy effectively integrates atomically dispersed iron onto N-C supports.
• Transmetalation approach enhances Fe site density and catalytic performance.
• This method offers a pathway to superior Fe-N-C catalysts for oxidation reactions.