Electrocatalytic Nitrate Reduction on Metallic CoNi-Terminated Catalyst with Industrial-Level Current Density in...

Area of Science:

• Electrochemistry
• Catalysis
• Green Chemistry

Background:

• The Haber-Bosch process for ammonia synthesis is energy-intensive.
• Electrocatalytic nitrate reduction reaction (eNO3RR) offers a greener alternative.
• Challenges remain in achieving high efficiency and current density in neutral media for eNO3RR.

Purpose of the Study:

• To design and construct an efficient electrocatalyst for ammonia synthesis via eNO3RR.
• To achieve high Faradaic efficiency (FE) at industrially relevant current densities in a neutral medium.
• To demonstrate the practical application potential of the developed catalyst system.

Main Methods:

• Theoretical calculations guided the design of a metallic CoNi-terminated catalyst.
• The catalyst was constructed on a copper foam support.
• Electrochemical performance was evaluated, including Faradaic efficiency and overpotential.
• Characterization techniques confirmed the catalyst's structure and properties.
• A homemade gas stripping and absorption device was used to demonstrate product conversion.

Main Results:

• The CoNi-terminated catalyst achieved 100% ammonia Faradaic efficiency.
• High ammonia yield was obtained at industrial-level current density.
• A very low overpotential of -0.15 V versus reversible hydrogen electrode was achieved in a neutral medium.
• Characterization confirmed the crucial role of the metal atom-terminated surface for performance.
• High-purity ammonium nitrate products were demonstrated, indicating practical potential.

Conclusions:

• A novel CoNi-terminated catalyst enables highly efficient and selective ammonia synthesis via eNO3RR.
• The catalyst overcomes key challenges of low efficiency and high overpotential in neutral media.
• This work presents a sustainable pathway for converting nitrate pollutants into valuable nitrogen fertilizers.