Molecular‐Level π‐Stacking Engineering in Dative B←N Frameworks for Superior Photocatalytic H ₂ O ₂ Production

Abstract

ABSTRACT The photocatalytic synthesis of hydrogen peroxide (H 2 O 2 ) from O 2 and H 2 O represents a sustainable alternative to the energy‐intensive anthraquinone process. However, achieving efficient photocatalysis requires precise control over structure–activity relationships, which remains a significant challenge. Herein, we report a molecular engineering strategy that leverages precise tuning of intermolecular π‐stacking in three single‐crystalline dative B←N frameworks (BNF‐75, ‐76, and ‐77). By systematically modulating the planarity of the B‐acceptors, we achieved a progressive decrease in the root‐mean‐square deviation (RMSD) of the B‐acceptors from 0.463 Å in BNF‐75 to 0.201 Å in BNF‐77. The BNF‐77 exhibits broadened visible‐light absorption, enhanced charge separation and transport, and an outstanding H 2 O 2 production rate of 5684.6 µmol·g −1 ·h −1 under visible light without sacrificial agents or metal cocatalysts (λ > 420 nm). Simple mechanical grinding for particle‐size reduction further elevates the rate to a remarkable 9451.0 µmol·g −1 ·h −1 , positioning BNF‐77 among the top‐performing crystalline photocatalysts based on dative B←N bonds. Integrated mechanistic studies reveal a synergistic mechanism: the dative B←N bond extends light harvesting and promotes charge separation, while the engineered tight π‐stacking constructs efficient charge‐transport highways and facilitates the two‐electron oxygen reduction reaction (ORR) pathway, with superoxide radicals (•O 2 − ) as the key intermediate.