Altering the Catalytic Activity of a Monomeric Cu-Porphyrin Using Self-Assembly To Preorganize a Cubic Architecture

Area of Science:

• Coordination chemistry
• Supramolecular chemistry
• Electrocatalysis

Background:

• Coordination-driven self-assembly enables the creation of polynuclear structures with preorganized catalytic sites.
• Metal-organic frameworks and coordination cages are increasingly explored for catalytic applications.

Purpose of the Study:

• To investigate the electrocatalytic behavior of a self-assembled copper porphyrin cube with iron nodes (Fe-Cu) for CO2 reduction reaction (CO2RR) and hydrogen evolution reaction (HER).
• To understand the influence of the self-assembled structure on catalytic activity and selectivity compared to its components.

Main Methods:

• Ultraviolet-visible (UV-vis) spectroscopy
• Cyclic voltammetry
• Spectroelectrochemical experiments
• X-ray photoelectron spectroscopy (XPS)

Main Results:

• The Fe-Cu cube decomposes to regenerate Cu-TAPP under catalytic conditions.
• Fe-Cu materials exhibit higher selectivity for HER, unlike Cu-TAPP which produces CO2RR products.
• The catalytic activity of Fe-Cu differs from Cu-TAPP and physical mixtures, even when the same active species are present.

Conclusions:

• Self-assembly can preorganize catalytic sites, and the resulting structure influences reaction pathways.
• The polynuclear microenvironment's limited molecular movement under heterogeneous conditions preserves unique catalytic properties despite assembly decomposition.
• This work highlights the potential of self-assembled structures in electrocatalysis, demonstrating how structural integrity affects selectivity.