Microenvironment Engineering in Pyridyl-Acetylene-Based Porous Organic Polymers for Enhanced H₂O₂ Photosynthesis

Artificial photosynthesis of hydrogen peroxide (H 2 O 2 ) from pure water and oxygen, without relying on sacrificial agents, offers a sustainable alternative to the conventional industrial anthraquinone method. Nevertheless, the insufficient proton (H + ) supply derived from the sluggish water oxidation limits the overall photocatalytic H 2 O 2 production rate. Herein, two pyridyl-acetylene-based porous organic polymers with identical skeletal structures but distinct substituents, namely, CH 3 -TEE-POP and NO 2 -TEE-POP, were synthesized by varying the substituent at the meta-position of the pyridinic nitrogen. The substituent at the meta-position of the pyridinic nitrogen influences the interaction between the pyridinic nitrogen and H 2 O molecules. Density functional theory analysis reveals that the interaction between the N atom in the CH 3 -TEE-POP skeleton and H 2 O molecules is stronger than that in NO 2 -TEE-POP, resulting in a more significant weakening of the O–H bond in water molecules. The weakening of the O–H bond facilitates the 4-electron water oxidation reaction to generate H + and O 2 and simultaneously promotes the consumption of holes, leading to an improvement in the overall photocatalytic efficiency. Consequently, CH 3 -TEE-POP achieves an exceptional initial H 2 O 2 production rate of 3183 μmol g cat –1 h –1, outperforming that of NO 2 -TEE-POP (1609 μmol g cat –1 h –1 ). This work highlights the pivotal role of microenvironmental engineering of porous organic polymer photocatalysts for achieving efficient H 2 O 2 production.