Engineering the NiNC Catalyst Microenvironment Enabling CO₂ Electroreduction with Nearly 100% CO Selectivity in...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Acidic CO2 electrolysis offers high CO2 utilization by preventing carbonate formation.
• Improving electrocatalyst efficiency and stability in acidic media is crucial.
• Tailoring the catalyst's microenvironment is key for enhanced performance.

Purpose of the Study:

• To optimize the microenvironment of a nickel-nitrogen-carbon (Ni-N-C) catalyst for acidic CO2 electrolysis.
• To investigate the effect of hydrophobic poly(tetrafluoroethylene) (PTFE) nanoparticles on catalyst performance.
• To enhance CO2 utilization efficiency and electrode stability.

Main Methods:

• Structurally engineered Ni-N-C catalyst modified with PTFE nanoparticles.
• Fabrication of gas-diffusion electrodes with modified catalytic layers.
• Electrochemical testing at industry-relevant current densities.
• Mechanistic investigations of the catalytic layer's microenvironment.

Main Results:

• PTFE-modified electrode achieved nearly 100% CO Faradaic efficiency at 250 mA cm-2.
• High single-pass CO2 utilization of 75.7% was observed at 200 mA cm-2.
• Enhanced water-flooding resistance compared to unmodified electrodes.
• Optimized local CO2/H2O ratio and reduced diffusion layer thickness.

Conclusions:

• Moderate PTFE modification creates a favorable interfacial microenvironment for acidic CO2 electrolysis.
• The optimized microenvironment enhances catalyst activity, stability, and CO2 utilization.
• PTFE-modified Ni-N-C catalysts represent a promising advancement for CO2 conversion technologies.