Promoting Dinuclear-Type Catalysis in Cu₁ -C₃ N₄ Single-Atom Catalysts.

Area of Science:

• Heterogeneous Catalysis
• Materials Science
• Organic Chemistry

Background:

• Single-atom catalysts (SACs) maximize metal atom efficiency but struggle with multi-reactant activation due to large inter-atom distances.
• Complex reactions often require cooperative activation of multiple reactants, a challenge for traditional SACs.

Purpose of the Study:

• To investigate controlling inter-atom distances in copper SACs to promote dinuclear-type coactivation.
• To explore the catalytic mechanism of nitrile-azide cycloaddition using tailored copper SACs.

Main Methods:

• Synthesis of copper SACs on carbon nitride (C3N4) with controlled inter-atom distances.
• Operando X-ray absorption fine structure (XAFS) spectroscopy to study dynamic processes.
• Kinetic analysis of the nitrile-azide cycloaddition reaction.

Main Results:

• Copper SACs with an average inter-atom distance of 0.74 ± 0.13 nm were successfully synthesized.
• A dinuclear catalytic mechanism involving dynamic ligand exchange and coactivation of nitrile and azide was revealed.
• The catalyst facilitated the formation of tetrazole products via cooperative activation on adjacent Cu sites.

Conclusions:

• Reducing the nearest-neighbor distance in SACs can shift catalytic mechanisms from single-site to multisite cooperative processes.
• Tailoring inter-atom distances is a viable strategy to enhance SACs for complex chemical transformations.
• This work provides insights into designing advanced catalysts for efficient multi-reactant activation.