Molecular Assembly Unlocks Dual-Defect Synergy in Carbon Nitride for Efficient H₂O₂ Photosynthesis.

Area of Science:

• Materials Science
• Catalysis
• Photochemistry

Background:

• Graphitic carbon nitride (g-C₃N₄) shows promise for photocatalytic hydrogen peroxide (H₂O₂) production.
• Achieving optimal g-C₃N₄ performance is hindered by a synthesis paradox, making it difficult to create essential dual active sites (nitrogen vacancies and cyano groups) simultaneously.

Purpose of the Study:

• To resolve the synthesis paradox in g-C₃N₄ for efficient H₂O₂ production.
• To develop a one-step strategy for creating K-doped g-C₃N₄ with synergistic dual defects.

Main Methods:

• A molecular assembly-molten salt coupling strategy was employed for the one-step synthesis of K-doped g-C₃N₄.
• Advanced characterization techniques and theoretical calculations were used to analyze the material's structure and properties.
• In situ analysis was performed to investigate the reaction mechanism and intermediate formation.

Main Results:

• The synthesized K-doped g-C₃N₄ exhibited an exceptional H₂O₂ production rate of 2.65 mmol·g^-1·h^-1, significantly outperforming pristine and physically-ground samples.
• Molecular assembly facilitated K⁺ interlayer embedding, enhancing charge migration.
• The dual defects demonstrated functional complementarity: nitrogen vacancies improved O₂ adsorption, and cyano groups aided proton coupling, leading to a facile two-step, single-electron pathway for H₂O₂ formation.

Conclusions:

• The molecular assembly-molten salt coupling strategy effectively resolves the synthesis paradox, enabling the rational design of dual-defect sites in g-C₃N₄.
• This approach provides a generalizable strategy for developing advanced photocatalysts for H₂O₂ production and other applications.
• The optimized K-doped g-C₃N₄ demonstrates superior performance due to synergistic effects between K⁺ intercalation and dual defects.