Long‐Wavelength Visible Griffith‐Type Oxygen Photoactivation on Isomeric Mesoporous Al‐Salen Covalent Organic Polymer Fibers

Abstract

ABSTRACT Covalent organic polymers (COPs) have emerged as promising photocatalysts for efficient solar‐driven conversion of energy into chemicals. However, it remains rare for COPs capable of effectively harvesting long‐wavelength visible to near‐infrared (L‐Vis‐NIR) light ( λ  > 600 nm) to achieve these photochemical transformations. Here, two isomeric mesoporous Al‐Salen COP fibers are demonstrated as L‐Vis‐NIR‐responsive photocatalysts for efficient Griffith‐type oxygen activation to produce hydrogen peroxide (H 2 O 2 ). Both COPs achieve a high H 2 O 2 production rate of about 1607 µmol g cat −1  h −1 under irradiation of common domestic LED lights (680–690 nm, 3.18 mW cm −2 ) using 1,2,3,4‐tetrahydroisoquinoline as a sacrificial reagent with a high solar to chemical efficiency of about 5.0%. Their efficient L‐Vis‐NIR‐responsive photocatalytic performance is attributed to their narrow band gaps of about 1.5 eV, efficient charge separation facilitated by integrated electron‐donor (benzene ring) and electron‐acceptor (Al‐Salen Lewis acid site) structures, and a direct Griffith‐type photo‐activation mechanism for oxygen. No significant isomerism effect is observed in their photocatalytic performance, attributed to the similar photoinduced charge carrier behaviors mainly affected by the local Al‐Salen moieties rather than the topological structure. This study highlights isomeric Al‐based COPs as effective platforms for L‐Vis‐NIR photocatalysis and opens avenues for the development of Al‐based COP photocatalysts for diverse chemical transformations.