Reactive magnetron sputtered copper nitride with controlled N-coordination number for ionic polymer free CO₂...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Copper nitride materials show promise for electrochemical CO2 reduction.
• The catalytic mechanism is often obscured by non-standard electrode fabrication methods.

Purpose of the Study:

• To investigate the mechanism of copper nitride catalysts for CO2 reduction.
• To optimize copper nitride electrode fabrication for enhanced C2+ product selectivity.
• To elucidate the role of copper-nitrogen coordination in catalytic activity.

Main Methods:

• Reactive magnetron sputtering for direct copper nitride deposition on gas diffusion layers.
• In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS).
• Density functional theory (DFT) calculations.

Main Results:

• A copper nitride electrode achieved 80.84% Faradaic efficiency for C2+ products at -0.68 V vs. RHE.
• A partial current density of 240 mA/cm2 was reached with a CuN coordination number of 2.48.
• DFT and experimental data identified CO protonation and C-C coupling as rate-determining steps.

Conclusions:

• Precise control of the CuN coordination number is crucial for balancing energy barriers.
• Optimizing coordination minimizes energy requirements for CO2 conversion to C2+.
• This study provides theoretical guidance for designing advanced copper-based CO2 reduction catalysts.