Unveiling Active Sites and Charge Carrier Dynamics in Copper–Phosphonobenzoate Photohybrids for Efficient H 2 O 2 Generation

ABSTRACT Solar‐driven, highly selective chemical transformation reactions remain a persistent challenge for artificial photosynthetic systems. Herein, two copper‐phosphonobenzoate photohybrid coordination polymers (PCPs), m ‐CBP and p ‐CBP, are introduced, highlighting distinct photocatalytic behavior arising from their structurally differentiated frameworks. Single‐crystal x‐ray diffraction reveals that the positional isomerism of the bifunctional phosphonobenzoate ligand, in combination with an auxiliary bipyridine, organizes Cu (II) centers into distinct coordination geometries and flexible framework dimensionalities. Although p ‐CBP exhibits a slightly narrower optical bandgap, m ‐CBP displays more favorable band alignment, lower O 2 adsorption energy and more efficient charge separation, resulting in markedly enhanced H 2 O 2 generation (1915 µmol g −1 h −1 ) under simulated solar irradiation. The paddle wheel Cu(II) creates shorter Cu…Cu contacts and extended delocalized pathways, which accelerate electron transfer to surface‐bound O 2 and facilitate two electron oxygen reduction (2e − ORR) pathway. In contrast, p‐ CBP featuring isolated square planar and octahedral sites exhibits localized charge density and diminished 2e − ORR selectivity. Furthermore, radical‐trapping experiments confirm a two‐electron pathway predominantly, and DFT studies reveal the energy profiles of O 2 adsorption sites. Together, these findings illustrate a design strategy for constructing framework architectures with regioisomeric bifunctional groups regulating coordination environments, charge transport and ORR selectivity, precisely tailoring structure‐property‐function dynamics in solar‐driven H 2 O 2 photosynthesis.