Overcoming Gas Mass Transfer Limitations Using Gas-Conducting Electrodes for Efficient Nitrogen Reduction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic nitrogen reduction reaction (NRR) offers a sustainable route for ammonia synthesis.
• Challenges include low nitrogen solubility and competing hydrogen evolution reaction (HER), limiting ammonia yield and Faraday efficiency.
• Existing electrodes struggle to optimize the three-phase interface (TPI) for efficient NRR.

Purpose of the Study:

• To design and demonstrate a novel gas-conducting electrode for enhanced electrocatalytic nitrogen reduction.
• To overcome mass transfer limitations and suppress the hydrogen evolution reaction (HER) in ammonia synthesis.
• To improve ammonia yield rate and Faraday efficiency in electrocatalytic NRR.

Main Methods:

• Fabrication of a Janus-Ni/MoO2@NF electrode with asymmetric gas wetting properties, inspired by lotus leaf superhydrophobicity/hydrophilicity.
• Electrochemical characterization of the Janus electrode for nitrogen reduction reaction (NRR) performance.
• Evaluation of ammonia yield rate and Faraday efficiency at various potentials, comparing with conventional electrodes.

Main Results:

• The Janus-Ni/MoO2@NF electrode created an abundant three-phase interface (TPI), enhancing N2, electrolyte, and electrode contact.
• The hydrophobic side of the Janus electrode repelled water, suppressing HER and increasing N2 concentration.
• Achieved a record-high NH3 yield rate of 5.865 μg·h−1·cm−2 and 36.14% Faradaic efficiency at 0 V vs RHE, significantly outperforming conventional electrodes.

Conclusions:

• The developed gas-conducting Janus electrode effectively breaks gas mass transfer limitations in electrocatalytic NRR.
• The asymmetric wetting design dramatically improves both activity and selectivity for ammonia synthesis.
• This interface engineering approach provides a promising strategy for other gas-involved sustainable electrochemical reactions.