High Ammonia Yield Rate from Dilute Nitrate Solutions Using a Cu(100)-Rich Foil: A Step Closer to Large-Scale...

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Chemistry

Background:

• Nitrate (NO3-) pollution in water poses environmental risks.
• Electrochemical reduction of NO3- to ammonia (NH3) offers a dual solution for pollution control and valuable chemical production.
• Current NH3 yield rates are limited, especially at dilute NO3- concentrations.

Purpose of the Study:

• To develop a scalable electrochemical method for producing a highly efficient NO3- to NH3 electrocatalyst.
• To investigate the catalytic performance of copper nanostructures enriched with (100) facets.
• To understand the fundamental catalytic differences between Cu(100) and Cu(111) facets using DFT calculations.

Main Methods:

• Fabrication of a Cu foil with a porous Cu nanostructure enriched with (100) facets.
• Electrochemical reduction of NO3- to NH3 under varying concentrations.
• Durability testing in a flow cell system.
• Density Functional Theory (DFT) calculations.

Main Results:

• The Cu(100)-rich catalyst achieved an NH3 production rate of 1.1 mmol h-1 cm-2 at 14 mM NO3-, significantly exceeding previous reports.
• At 140 mM NO3-, the NH3 yield rate increased to 3.34 mmol h-1 cm-2.
• The catalyst demonstrated over 100 hours of stability with >98% Faradaic efficiency.
• DFT calculations confirmed the superior catalytic activity of Cu(100) for NO3- reduction.

Conclusions:

• A scalable and highly efficient electrocatalyst for NO3- reduction to NH3 has been developed.
• The Cu(100) facet plays a crucial role in enhancing catalytic activity.
• The catalyst shows significant potential for industrial applications in wastewater treatment and NH3 synthesis.