Efficient Photocatalytic H ₂ O ₂ Production by Pyridine-Based Donor–Acceptor Polymers under Visible Light Irradiation without Any Additives

Although donor–acceptor (D-A) organic polymers offer structural tunability and metal-free advantages, their practical application is hindered by high cost, low efficiency, and the requirement of sacrificial agents. To date, no D–A polymer catalysts derived from low-cost 2,6-diaminopyridine (DAP) and terephthalaldehyde (TAP) have been reported. In this work, we synthesized a pyridine-based polymer (HPs) via green water-mediated and catalyst-free multicomponent reactions. The resulting material achieved a H2O2 production rate of 998.0 μmol·gcat–1·h–1 without additives or O2 aeration, representing a 2.3-fold enhancement over the surfactant-free polymer. Detailed characterizations revealed that the dual surfactants not only induced the formation of the multichambered structure but also regulated the imine content in the catalyst, thereby modifying its bandgap structure and enhancing photocurrent intensity. Mechanistic studies revealed that the directional transfer of photoexcited electrons from the pyridine ring to the benzene ring drove oxygen reduction reactions (ORR) to produce H2O2, while residual holes on the pyridine facilitate water oxidation (WOR) to supply protons. The low electron–hole overlap (0.15) further confirms the HPs’ capability in inhibiting charge recombination. This study presents a low-cost, highly efficient polymer with significant potential for artificial photosynthesis applications.