Edge-Functionalized Metal-Free Polyphthalocyanine Networks for Efficient Photocatalytic H₂O₂ Production

Hydrogen peroxide (H₂O₂) is a green oxidant with wide applications, but its industrial production via the anthraquinone process is energy-intensive and environmentally harmful. Photocatalytic H₂O₂ generation from water and oxygen under visible light offers a sustainable alternative, although current systems suffer from poor light absorption and fast charge recombination. Here, we report a molecular engineering strategy to enhance the photocatalytic H₂O₂ generation of phthalocyanine-based covalent polymers (PPc) by introducing naphthyl groups at the polymer edge. The resulting PPc-n shows a 2.77-fold improvement in the H₂O₂ production rate (174.15 μmol·g^-1·h^-1) compared to unmodified PPc-p under visible light with ethanol as a sacrificial agent. Mechanism studies, including EPR spectroscopy and reactive species trapping, reveal that PPc-n follows a two-step, single-electron oxygen reduction pathway, with •O₂^- as the key intermediate. This work highlights edge functionalization as an effective approach to enhancing light harvesting and charge separation in organic photocatalysts for green chemical synthesis.