Designing Molecular Reactor of Interlayer Dual-Atom Toward Urea Electrosynthesis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Traditional industrial urea synthesis is energy-intensive.
• Electrocatalytic C-N coupling presents a sustainable alternative.
• Developing efficient electrocatalysts is crucial for green urea production.

Purpose of the Study:

• To design and investigate conjugated polymer-based molecular reactors for electrocatalytic urea synthesis.
• To optimize CO2 and nitrate coupling by tuning interlayer spacings and diatomic Cu-N4 sites.
• To understand the structure-activity relationship for enhanced C-N coupling.

Main Methods:

• Synthesis of conjugated polymer molecular reactors with varying interlayer spacings (4.0, 4.6, 5.7 Å).
• Electrocatalytic testing of synthesized materials for urea synthesis.
• Characterization and mechanistic studies to elucidate the role of interlayer spacing and Cu-N4 sites.
• Comparison with ball-milling treated catalysts.

Main Results:

• The 4.0 Å-spaced copper polyphthalocyanine (CuPPc-4.0) achieved a high urea yield rate of 460.0 mmol h⁻¹ g⁻¹ with 26.1% Faradaic efficiency at -1.3 V.
• Optimal 4.0 Å cavity enhances C-N coupling by spatially confining reactants and intermediates, matching urea's molecular dimensions.
• Layered AA stacking structure stabilizes diatomic Cu configurations, preventing aggregation and ensuring catalyst durability.
• Ball-milling treatment, while increasing single-atom exposure, disrupted the structure and reduced activity by ~50%.

Conclusions:

• Multidimensional catalyst design integrating atomic precision and molecular confinement is effective for sustainable electrosynthesis.
• Precisely tuned interlayer spacing in conjugated polymers is key to optimizing electrocatalytic urea synthesis.
• The CuPPc-4.0 catalyst demonstrates a promising pathway for efficient and sustainable urea production.