Study on Fe/BZY Cathode Catalysts for Intermediate-Temperature Electrochemical Ammonia Synthesis Using Solid...

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Electrochemical ammonia (NH3) synthesis offers a sustainable alternative to the Haber-Bosch process.
• Intermediate-temperature operation is desirable for energy efficiency and catalyst stability.
• Solid-state electrolytes are crucial for developing robust electrochemical cells.

Purpose of the Study:

• To develop an efficient base-metal cathode for electrochemical NH3 synthesis.
• To investigate the role of cathode composition and processing on NH3 formation.
• To demonstrate NH3 synthesis using a solid-state Cs phosphate electrolyte.

Main Methods:

• Electrochemical cell fabrication with a Cs phosphate-based electrolyte.
• Development of a Fe/BZY (yttrium-doped barium zirconate) cathode catalyst by combining Fe2O3/BZY reduced at different temperatures (500°C and 800°C).
• Electrochemical performance evaluation, including NH3 production rate measurements at varying potentials.

Main Results:

• A Fe/BZY cathode catalyst was successfully developed, enabling NH3 formation at intermediate temperatures (ca. 220°C).
• Metallic Fe, formed above 700°C in the cathode, provided an essential electronic conduction path.
• Potassium (K) addition to the cathode significantly enhanced the NH3 production rate to 1.3 × 10^-10 mol s^-1 cm^-2 at -1.0 V (vs. OCV).

Conclusions:

• This study reports the first successful electrochemical NH3 synthesis using a base-metal cathode with a solid-state Cs phosphate electrolyte.
• The developed Fe/BZY cathode, optimized through specific reduction temperatures and K addition, shows promise for efficient NH3 production.
• Intermediate-temperature electrochemical NH3 synthesis is feasible with carefully designed solid-state electrochemical cells.