Efficient Electrochemical Urea Synthesis From CO₂ and N₂ in Moderate Pressure

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis
• Sustainable Chemistry

Background:

• Electrochemical nitrogen fixation offers a sustainable route for nitrogen cycle management using renewable energy.
• Aqueous systems face challenges with hydrogen evolution reaction dominating over nitrogen (N₂) activation, limiting production rates and efficiency.
• Existing methods struggle to balance high urea production rates with efficient nitrogen fixation.

Purpose of the Study:

• To develop a novel strategy for enhancing electrochemical nitrogen fixation in aqueous systems.
• To improve urea synthesis by suppressing gaseous byproducts (CO/H₂) and promoting carbon-nitrogen (C-N) coupling.
• To engineer an advanced catalyst for efficient and selective nitrogen conversion.

Main Methods:

• Coupling an engineered pressure field with an electrochemical N₂-CO₂ co-fed urea synthesis system.
• Development of atomically dispersed amorphous Bi_xNi_1-xO_y clusters as a tandem catalyst.
• In situ characterization to confirm pressure-driven electronic modulation of the catalyst's active sites.

Main Results:

• Achieved a high urea production rate of 8.71 mmol h^-1 g^-1_cat.
• Demonstrated a remarkable 50% nitrogen fixation efficiency, significantly suppressing CO/H₂ evolution.
• Confirmed pressure-induced electronic modulation: Bi sites oxidized, Ni sites reduced, enhancing catalytic activity.

Conclusions:

• The integration of pressure engineering with atomic-scale catalyst design provides a new paradigm for gas-involved electrochemical reactions.
• This approach offers a guiding strategy for optimizing catalysts and reaction conditions in electrochemical nitrogen fixation.
• The developed Bi-Ni catalyst and pressure system represent a significant advancement for sustainable urea production.