Highly distributed amorphous copper catalyst for efficient ammonia electrosynthesis from nitrate.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Nitrate electroreduction to ammonia is crucial for pollution control and chemical production.
• Crystalline metallic catalysts enhance ammonia evolution, but amorphous catalysts remain underexplored.
• Amorphous catalysts offer potential for increased active sites and improved efficiency.

Purpose of the Study:

• To develop and investigate highly distributed amorphous copper (Cu) catalysts for nitrate electroreduction to ammonia.
• To compare the performance of amorphous Cu catalysts with crystalline Cu catalysts.
• To elucidate the mechanism behind the enhanced catalytic activity of amorphous Cu.

Main Methods:

• Synthesis of a highly distributed amorphous Cu catalyst.
• Electrochemical evaluation of nitrate reduction to ammonia, measuring yield rate and Faradaic efficiency.
• Experimental and computational studies to understand the catalytic mechanism.
• Assessment of electrochemical stability at various potentials.

Main Results:

• The amorphous Cu catalyst achieved an outstanding ammonia yield rate of 1.42 mol h⁻¹ g⁻¹ and a Faradaic efficiency of 95.7%.
• Amorphization of Cu increased catalytic sites, enhanced nitrate adsorption, and facilitated the *NO protonation step.
• The amorphous Cu catalyst demonstrated good stability at -0.3 V, outperforming crystalline Cu.

Conclusions:

• Amorphous Cu catalysts are highly effective for nitrate electroreduction to ammonia, surpassing crystalline counterparts.
• The study confirms a strong relationship between catalyst crystallinity and activity in amorphous materials.
• Amorphous catalysts offer a promising avenue for efficient pollution control and value-added chemical synthesis, though potential-limited stability needs consideration.