Electrocatalytic nitrogen reduction to ammonia by atomically precise Cu₆ nanoclusters supported on graphene oxide

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic nitrogen reduction reaction (NRR) offers a sustainable route for ammonia synthesis using renewable energy.
• Challenges include the inertness of nitrogen gas (N₂) and competing hydrogen evolution reaction (HER) in aqueous electrolytes, reducing efficiency.
• Developing efficient electrocatalysts is crucial for ambient ammonia production.

Purpose of the Study:

• To synthesize and investigate the electrocatalytic performance of Cu₆(SMPP)₆ nanoclusters (Cu₆ NCs) immobilized on graphene oxide (GO) for the nitrogen reduction reaction (NRR).
• To understand the mechanism of NRR enhancement by the Cu₆ NCs/GO system.
• To evaluate the ammonia yield rate and faradaic efficiency of the developed electrocatalyst.

Main Methods:

• Synthesis of Cu₆(SMPP)₆ nanoclusters and their immobilization on graphene oxide.
• Electrocatalytic testing using an H-cell setup to measure ammonia production.
• Quantum chemistry calculations to elucidate the reaction mechanism and energy barriers.

Main Results:

• The GO-supported Cu₆ NCs demonstrated a high ammonia yield rate of 4.8 μg h^-1 cm^-2.
• Achieved a high faradaic efficiency of up to 30.39% for ammonia production at a potential of -1.1 V.
• Computational studies indicated facilitated N₂ adsorption and activation on the Cu₆S₆ cluster/GO surface.

Conclusions:

• The Cu₆ NCs/GO electrocatalyst significantly enhances the nitrogen reduction reaction performance.
• The catalyst design effectively suppresses hydrogen evolution and promotes ammonia synthesis.
• This work provides a promising strategy for developing efficient electrocatalysts for sustainable ammonia production.