Spatially Separated Activation-Conversion Nitride Catalysts for Accelerated Ammonia Synthesis.

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• Ammonia synthesis is crucial for industry and energy, but limited by scaling relationships.
• Existing catalysts face challenges in balancing reaction steps for optimal efficiency.

Purpose of the Study:

• To design a novel triphase heterostructure catalyst for efficient ammonia synthesis.
• To overcome the intrinsic Sabatier limitation in catalytic ammonia production.

Main Methods:

• Constructed a Ni₂Mo₃N host integrated with Mo₂N domains and metallic Ni nanoparticles.
• Employed a solid-solution reaction for catalyst synthesis.
• Conducted mechanistic studies to elucidate the catalytic pathway.

Main Results:

• The catalyst achieved a high ammonia synthesis rate of 32.5 mmol·g⁻¹·h⁻¹ at 500 °C and 1.0 MPa.
• Demonstrated nearly threefold improvement over the Ni₂Mo₃N reference catalyst.
• Identified a spatially separated activation-conversion pathway facilitated by metallic Ni and nitrogen vacancies.

Conclusions:

• The developed catalyst effectively decouples conflicting elementary steps in ammonia synthesis.
• Establishes a general design paradigm for tandem catalytic architectures using spatial synergy.
• Offers a viable route to surpass Sabatier limitations in catalysis.