Enhancement of lithium-mediated ammonia synthesis by addition of oxygen

2021/12/23 by Katja Li, Suzanne Z. Andersen, Michael J. Statt +12 · 1 citation
Chemical Engineering · Energy · Materials Science · #Advanced Photocatalysis Techniques #Ammonia Synthesis and Nitrogen Reduction #Hydrogen Storage and Materials

paper · doi:10.1126/science.abl4300

openalex publication_date 2021/12/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23

Abstract

Owing to the worrying increase in carbon dioxide concentrations in the atmosphere, there is a need to electrify fossil-fuel–powered chemical processes such as the Haber-Bosch ammonia synthesis. Lithium-mediated electrochemical nitrogen reduction has shown preliminary promise but still lacks sufficient faradaic efficiency and ammonia formation rate to be industrially relevant. Here, we show that oxygen, previously believed to hinder the reaction, actually greatly improves the faradaic efficiency and stability of the lithium-mediated nitrogen reduction when added to the reaction atmosphere in small amounts. With this counterintuitive discovery, we reach record high faradaic efficiencies of up to 78.0 ± 1.3% at 0.6 to 0.8 mole % oxygen in 20 bar of nitrogen. Experimental x-ray analysis and theoretical microkinetic modeling shed light on the underlying mechanism.

Citations

• How a century of ammonia synthesis changed the world
• Non-aqueous gas diffusion electrodes for rapid ammonia synthesis from nitrogen and water-splitting-derived hydrogen
• A Roadmap to the Ammonia Economy
• Increasing stability, efficiency, and fundamental understanding of lithium-mediated electrochemical nitrogen reduction
• Identification and elimination of false positives in electrochemical nitrogen reduction studies
• Recent progress in electrochemical synthesis of ammonia from nitrogen: strategies to improve the catalytic activity and selectivity
• Electrochemical ammonia synthesis: Mechanistic understanding and catalyst design
• Nitrogen reduction to ammonia at high efficiency and rates based on a phosphonium proton shuttle
• Methods for nitrogen activation by reduction and oxidation

Cited by

• Catalyst screening for electrochemical ammonia synthesis: a critical review

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• Continuous-flow electrosynthesis of ammonia by nitrogen reduction and hydrogen oxidation
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