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.