Selective Electrosynthesis of Ammonia via Sequential Electron-Proton Transfer

Area of Science:

• Electrochemistry
• Catalysis
• Sustainable Energy

Background:

• Proton-coupled electron transfer (PCET) is vital for energy conversion, like nitrate reduction to ammonia (NO3RR).
• Decoupling electron transfer (ET) and proton transfer (PT) can improve NO3RR efficiency by preventing unwanted side reactions.

Purpose of the Study:

• To demonstrate a novel catalyst using π-conjugated cyanamide (NCN2-) groups for decoupled ET and PT in NO3RR.
• To enhance catalytic activity and product selectivity for ammonia synthesis.

Main Methods:

• Utilized π-conjugated cyanamide (NCN2-) functionalized catalysts with flexible structures.
• Employed in situ experimental characterizations and molecular dynamic modeling to validate the ETPT mechanism.
• Integrated the catalyst into a paired electro-refinery system for ammonia production.

Main Results:

• The NCN2- groups acted as an electron accelerator and proton relay, enabling a sequential electron transfer-proton transfer (ETPT) process.
• Achieved a high Faradaic efficiency of 95.3% for ammonia (NH3) production.
• Demonstrated stable operation for over 500 hours at an industrial current density (500 mA cm-2).

Conclusions:

• Sequential ETPT regulation using NCN2- is a viable strategy for optimizing PCET-mediated reactions.
• This approach significantly enhances performance in electrochemical nitrate reduction for sustainable ammonia synthesis.