Molecular-Level π-Stacking Engineering in Dative B←N Frameworks for Superior Photocatalytic H₂O₂ Production.

Area of Science:

• Materials Science
• Photocatalysis
• Sustainable Chemistry

Background:

• Photocatalytic synthesis of hydrogen peroxide (H₂O₂) offers a sustainable alternative to the energy-intensive anthraquinone process.
• Efficient photocatalysis is hindered by challenges in controlling structure-activity relationships.
• Dative B←N frameworks are explored for their potential in photocatalytic applications.

Purpose of the Study:

• To develop a molecular engineering strategy for enhancing H₂O₂ photocatalytic synthesis.
• To investigate the effect of intermolecular π-stacking and B-acceptor planarity on photocatalytic performance.
• To achieve high H₂O₂ production rates using single-crystalline dative B←N frameworks.

Main Methods:

• Synthesis of three single-crystalline dative B←N frameworks (BNF-75, -76, -77) with systematically modulated B-acceptor planarity.
• Characterization of structural properties, including root-mean-square deviation (RMSD) of B-acceptors.
• Evaluation of photocatalytic H₂O₂ production under visible light, including mechanistic studies and particle-size reduction via grinding.

Main Results:

• A progressive decrease in B-acceptor RMSD from 0.463 Å (BNF-75) to 0.201 Å (BNF-77) was achieved.
• BNF-77 demonstrated broadened visible-light absorption, enhanced charge separation and transport.
• BNF-77 achieved a H₂O₂ production rate of 5684.6 µmol·g⁻¹·h⁻¹ (visible light, no sacrificial agents/cocatalysts), further increased to 9451.0 µmol·g⁻¹·h⁻¹ after grinding.

Conclusions:

• The engineered dative B←N framework (BNF-77) exhibits excellent performance in visible-light photocatalytic H₂O₂ production.
• The dative B←N bond and tight π-stacking synergistically enhance light harvesting, charge separation, and charge transport.
• This work positions BNF-77 as a top-performing crystalline photocatalyst for H₂O₂ synthesis, highlighting the importance of molecular engineering.