Alkoxy Side Chains Enhance the Photocatalytic H2O2 Production over D -Glucuronolactone-Based Polymers with a Three-Dimensional Network

Abstract Current polymer photocatalysts predominantly depend on petrochemical resources and exhibit low charge separation efficiency, alongside ambiguous active sites. These limitations hinder the effectiveness of photocatalytic H2O2 synthesis. To address these challenges, herein we use biomass-derived monomers D-glucuronolactone as a building block and synthesize a series of three-dimensional crosslinked network polymer photocatalysts via a stepwise Schiff base condensation strategy. The effects of four side‑chain substituents—ethoxy, allyloxy, propoxy, and hydrogen—were systematically compared. These results demonstrate that the three-dimensional crosslinked framework markedly enhances both the stability and intrinsic charge-separation ability of the material. Furthermore, the ethoxy side chains strengthen intermolecular π–π stacking interactions, thereby optimizing charge transport efficiency and carrier separation. The as-synthesized target product GPA affords a H2O2 production rate of 4111 μmol g–1 h–1 under visible-light irradiation, which far surpasses all reference samples. Mechanistic studies reveal that the ethoxy side chain, in conjunction with the three-dimensional backbone, synergistically promotes proton-coupled electron transfer, which accounts for the observed performance enhancement. This study provides a novel molecular-level strategy for the rational design of high-performance biomass-based photocatalysts.