Ru₃@Mo₂CO₂ MXene single-cluster catalyst for highly efficient N₂-to-NH₃ conversion

Area of Science:

• Heterogeneous Catalysis
• Materials Science
• Computational Chemistry

Background:

• Single-cluster catalysts (SCCs) offer tunable performance for complex redox reactions.
• MXene supports are emerging materials for anchoring well-defined catalytic sites.
• Efficient nitrogen (N₂) to ammonia (NH₃) conversion remains a critical challenge in catalysis.

Purpose of the Study:

• To theoretically investigate the catalytic mechanism of a Ru₃@Mo₂CO₂ MXene SCC for N₂-to-NH₃ thermal conversion.
• To understand the role of the MXene support in activating N₂ and facilitating ammonia synthesis.
• To evaluate the catalytic performance and compare it with existing systems.

Main Methods:

• Density Functional Theory (DFT) calculations to study reaction pathways and energy barriers.
• Analysis of charge transfer and electronic structure of the catalyst-adsorbate system.
• Microkinetic analysis to determine turnover frequencies under specific conditions.

Main Results:

• Ru₃@Mo₂CO₂ effectively activates N₂ through an association mechanism with a low rate-determining step energy barrier (1.29 eV).
• The Mo₂CO₂ support facilitates N₂ activation via significant charge transfer (0.74 |e|) to the positively charged Ru₃ cluster.
• Calculated turnover frequency reached 1.45 × 10^-2 s^-1 site^-1 at 48 bar and 700 K, outperforming known catalysts like Ru B5 and Fe₃/θ-Al₂O₃(010).

Conclusions:

• The Ru₃@Mo₂CO₂ MXene SCC demonstrates high stability and efficiency for ammonia synthesis.
• The study provides theoretical insights into the catalytic mechanism and the role of MXene supports.
• Results guide the design of advanced MXene-based SCCs for mild-condition ammonia production.