Atomically Paired Cu-Co Dual Sites for Near-Unity Ammonia Selectivity in Nitrate Electroreduction.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical nitrate-to-ammonia conversion offers sustainable ammonia synthesis and environmental remediation.
• Achieving industrial current densities requires atomic-level control over catalytic sites for efficient proton-coupled electron transfer.
• Existing methods face challenges in selectivity and efficiency at high reaction rates.

Purpose of the Study:

• To develop a catalyst with atomically integrated dual sites for enhanced nitrate-to-ammonia conversion.
• To achieve high ammonia selectivity and current density under industrially relevant conditions.
• To investigate the role of atomic proximity of dual sites in overcoming kinetic barriers.

Main Methods:

• Fabrication of an interpenetrating polymer network integrating immiscible Cu and Co sites.
• Utilizing a polymer architecture combining poly(styrenesulfonate) and poly(3,4-ethylenedioxythiophene) with polypyrrole bridges.
• Electrochemical testing in a two-electrode flow cell under varying conditions (20 °C and 60 °C).
• Operando studies to confirm catalyst performance and mechanism.

Main Results:

• Achieved 99% ammonia Faradaic efficiency at 3.5 A cm⁻² with 200-h stability at 20 °C.
• Demonstrated 7.3 A cm⁻² current density for simultaneous ammonia and oxygen production at 60 °C and 1.6 V.
• Atomic Cu-Co proximity was confirmed to accelerate intermediate hydrogenation and overcome kinetic limitations.

Conclusions:

• The developed interpenetrating polymer network effectively integrates Cu and Co dual sites at the atomic level.
• This dual-active-site engineering approach enables high-throughput ammonia electrosynthesis with excellent selectivity and stability.
• The findings bridge molecular catalyst design with industrial electrocatalysis for sustainable ammonia production.