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Single atom coordination in a manganese-cobalt bi-metallic framework on graphene: geometric and electronic structures
Stefania Baronio1, Michela De Col1, Asha Yadav2
1Department of Physics, University of Trieste, via A. Valerio 2, Trieste 34127, Italy. evesselli@units.it.
Nanoscale
|July 7, 2025
Summary
Manganese and cobalt porphyrins self-assemble on graphene, forming a bimetallic network. This ordered structure reveals unique electronic properties and coordination states for both metals.
Area of Science:
- Materials Science
- Surface Chemistry
- Nanotechnology
Background:
- Manganese tetra-pyridyl-porphyrins (MnTPP) are known for their unique electronic and catalytic properties.
- Graphene serves as a versatile 2D substrate for self-assembly of molecular layers.
- Controlling the self-assembly of metal-organic complexes on surfaces is crucial for designing advanced functional materials.
Purpose of the Study:
- To investigate the self-organization of manganese tetra-pyridyl-porphyrins on graphene.
- To explore the effect of cobalt ad-atom deposition on the molecular layer.
- To characterize the resulting bimetallic network's geometric and electronic structure.
Main Methods:
- Scanning Tunneling Microscopy (STM) for surface imaging and structural analysis.
- X-ray Photoelectron Spectroscopy (XPS) for determining oxidation states.
- Density Functional Theory (DFT) calculations for electronic structure investigations.
Main Results:
- Ordered monolayer self-assembly of MnTPP on graphene observed.
- Cobalt ad-atoms induced geometric reordering, forming a bimetallic network.
- Mn shifted towards +2/+3 oxidation states, Co stabilized at +1 oxidation state.
- Lateral interactions within the network dominated over graphene-network bonding.
Conclusions:
- A novel self-assembled bimetallic network of Mn and Co porphyrins on graphene was successfully fabricated.
- The study reveals unique coordination environments and oxidation states for Mn and Co within the network.
- The findings highlight the potential for surface-assisted self-assembly in creating tailored nanomaterials with tunable electronic properties.
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