Revealing Mechanisms of Lithium-Mediated Nitrogen Reduction Reaction from First-Principles Simulations.

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Lithium-mediated nitrogen reduction reaction (Li-NRR) presents an eco-friendly alternative for ammonia electrosynthesis.
• Li-NRR offers advantages over the energy-intensive Haber-Bosch process and direct electrocatalytic nitrogen reduction reaction (NRR) with its kinetic and efficiency limitations.
• The precise reaction mechanisms and the role of the solid electrolyte interface (SEI) in Li-NRR remain largely unelucidated.

Purpose of the Study:

• To elucidate the reaction mechanisms of Li-NRR using theoretical calculations.
• To investigate the role of the SEI layer, particularly lithium and lithium nitride surfaces, in activating N2.
• To uncover novel pathways for ammonia electrosynthesis via Li-NRR.

Main Methods:

• Utilized electronic structure theory to model and analyze reaction pathways.
• Investigated mechanisms on lithium and lithium nitride surfaces, key SEI components.
• Compared discovered pathways with conventional direct electrocatalytic NRR.

Main Results:

• Discovered a nitridation-coupled reduction mechanism on lithium surfaces.
• Identified a nitrogen cycling reduction mechanism on lithium nitride surfaces.
• Demonstrated that surface reconstruction plays a crucial role in enhancing reactivity.

Conclusions:

• Li-NRR follows distinct pathways compared to direct electrocatalytic NRR.
• The SEI layer, through its components like lithium and lithium nitride, is critical for N2 activation.
• Findings provide insights for optimizing ammonia electrosynthesis efficiency.