Rational Design of Conductive MOF-Based Diatomic Electrocatalysts for Selective Ammonia Synthesis

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Diatomic catalysts (DACs) show promise exceeding single-atom catalysts (SACs) but face design and synthesis challenges.
• Ammonia synthesis from nitrate is crucial but requires highly selective and efficient catalysts.

Purpose of the Study:

• To demonstrate the design and synthesis of DACs for selective ammonia synthesis from nitrate.
• To elucidate the nitrate reduction mechanism using a tunable platform catalyst.

Main Methods:

• Development of a water-stable conductive metal-organic framework (cMOF) with tunable Cu and Ni nodes (Cu_xNi_y-DBCO).
• Systematic identification of active diatomic species and mechanistic studies.
• Synthesis and testing of an optimized DACs catalyst (Cu_98.5Ni_1.5-DBCO).

Main Results:

• The optimized Cu_98.5Ni_1.5-DBCO catalyst achieved unit selectivity for ammonia synthesis from nitrate.
• High ammonia yields of over 200 mg h^-1 mg_cat^-1 were obtained at a current density >750 mA cm^-2.
• A Zn-NO₃^- battery utilizing the DACs cathode demonstrated a power density of 35.6 mW cm^-2.

Conclusions:

• Conductive MOFs provide a viable platform for designing targeted diatomic catalysts.
• The developed DACs show significant potential for industrial electrocatalysis, particularly in ammonia synthesis.
• This work advances the field of diatomic catalysis and MOF-based electrocatalysts.