Flower-Inspired Chrysanthemum-Structured Photocatalyst Enabling Visible-Light-Driven CO ₂ Reduction to Formic Acid and the Synthesis of Pyrano-Fused Benzophenazines

The sustainable use of solar energy to drive multielectron catalytic processes is one feasible route toward the production of carbon-neutral compounds. In this study, we created a light-harvesting TTfCOF photocatalyst that resembles a chrysanthemum flower. Condensing 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (T) with triformyl phloroglucinol (Tf) yields a robust two-dimensional covalent chemical framework. The remarkable photoredox activity of the modified COFs enables highly effective visible-light-driven NADH regeneration (65.27%), demonstrating that it can enable multielectron transfer with minimal energy loss. Beyond recycling cofactors, the chrysanthemum-flower-like TTfCOF platform efficiently uses solar energy to reduce CO2, generating 156.65 μmol of formic acid, demonstrating its potential for environmentally friendly solar-to-fuel conversion. Additionally, the chrysanthemum-flower-like TTfCOF photocatalyst and Fe3O4 nanoparticles combine to form a synergistic catalytic interface that significantly enhances the synthesis of pyrano-fused benzophenazines, producing remarkable outcomes (up to 76%). This integrated photocatalytic system shows how cofactor regeneration, CO2 valorization, and value-added synthesis may all be combined in a single solar-activated system. All things considered, our research produces a flexible 2D-COF design that can speed up the development of solar-powered chemical production platforms and enable sustainable catalytic cascades.