Asymmetric polarization engineering of covalent triazine frameworks for efficient hydrogen peroxide photosynthesis

Covalent triazine frameworks (CTFs) show great potential in photocatalytic hydrogen peroxide (H 2 O 2 ) synthesis, yet conventional CTFs suffer from weak internal electric fields and serious photogenerated charge recombination. Herein, we report an asymmetric polarization engineering strategy by constructing two isostructural CTFs (CTF-1 and CTF-P1) through replacing benzene with asymmetric naphthalene units. Without altering the framework topology, naphthalene introduction breaks charge distribution symmetry, enhancing intramolecular and in-plane polarization to establish a stronger internal electric field. CTF-P1 exhibits a 216-fold higher dipole moment (0.216 D vs 0.001 D) and doubled polarizability compared to CTF-1, leading to optimized electronic structure, red-shifted light absorption, and significantly improved charge separation efficiency. Consequently, CTF-P1 achieves H 2 O 2 production rate of 2762 μmol g −1 h −1 in pure water without sacrificial agents, ∼10 times higher than that of CTF-1, along with excellent cycling stability and air applicability. Mechanistic studies reveal a synergistic two-electron oxygen reduction and water oxidation pathways. This work establishes asymmetric polarization as an effective molecular design principle for high-performance organic photocatalysts.