CO₂ Electroreduction in Water with a Heterogenized C-Substituted Nickel Cyclam Catalyst

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Molecular catalysts enable selective carbon dioxide (CO2) electroreduction to carbon monoxide (CO).
• Immobilizing catalysts on solid supports is crucial for practical applications in electrolytic cells, offering benefits like product separation, enhanced electron transfer, and stability.
• This immobilization strategy for molecular CO2 electroreduction catalysts remains underexplored.

Purpose of the Study:

• To develop a novel immobilized molecular catalyst for selective CO2 electroreduction to CO.
• To investigate the performance of the immobilized catalyst in both organic and aqueous media.
• To create a robust electrode material for efficient CO2 conversion.

Main Methods:

• Synthesis of a novel [Ni(cyclam)]2+ complex with a modified cyclam ligand.
• Immobilization of the nickel complex onto carbon nanotubes.
• Deposition of the functionalized carbon nanotubes onto a gas diffusion layer to create a novel electrode.
• Electrochemical characterization using controlled potential electrolysis in H-cells.

Main Results:

• The novel immobilized [Ni(cyclam)]2+ complex on carbon nanotubes exhibits remarkable selectivity for CO2 electroreduction to CO.
• High faradaic efficiencies for CO production (>90%) were achieved.
• The electrode demonstrated effective performance in both organic solvents and, notably, in water, with current densities of 5-10 mA cm-2.

Conclusions:

• The developed immobilized nickel-cyclam catalyst on carbon nanotubes represents a significant advancement in CO2 electroreduction technology.
• The electrode's ability to operate effectively in water broadens its potential applications for sustainable chemical synthesis.
• This work highlights the potential of immobilized molecular catalysts for efficient and selective electrochemical CO2 conversion.