Self-Tandem Electrocatalytic NO Reduction to NH₃ on a W Single-Atom Catalyst

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Nitrate reduction reaction (NORR) is crucial for environmental remediation and ammonia synthesis.
• Developing efficient and durable catalysts for NORR remains a significant challenge.
• Single-atom catalysts offer unique advantages in catalytic activity and selectivity.

Purpose of the Study:

• To design and synthesize a highly active and durable single-atom catalyst for NORR.
• To elucidate the catalytic mechanism of single-atom tungsten confined in amorphous molybdenum oxide nanosheets (W1/MoO3-).
• To achieve high ammonia yield and selectivity through an optimized NORR pathway.

Main Methods:

• Synthesis of single-atom W confined in MoO3- amorphous nanosheets (W1/MoO3-).
• Theoretical calculations and operando spectroscopic investigations.
• Electrochemical measurements to evaluate catalytic performance.

Main Results:

• W1/MoO3- exhibits excellent activity and durability for NORR.
• The W1-O5 motifs facilitate NO activation, protonation, and H2O dissociation.
• A self-tandem NORR mechanism accelerates the NO-to-NH3 pathway.
• Achieved 91.2% NH3-Faradaic efficiency and 308.6 μmol h-1 cm-2 NH3 yield rate.

Conclusions:

• Single-atom W confined in MoO3- amorphous nanosheets is a highly effective NORR catalyst.
• The unique W1-O5 motifs enable a self-tandem mechanism for enhanced proton supply and NO reduction.
• W1/MoO3- surpasses the performance of most previously reported NORR catalysts, offering a promising route for sustainable ammonia production.