Highly efficient photocatalytic generation of hydrogen peroxide via pyrene-anthraquinone structural covalent organic frameworks

Abstract

Covalent organic frameworks (COFs) constitute a novel category of porous materials that exhibit considerable promise for photocatalysis, particularly in the production of hydrogen peroxide (H₂O₂). A novel COF distinguished by a pyrene-anthraquinone architecture (denoted as Py-DQ-COF) was successfully prepared through a solvothermal process. The pyrene moiety acts as an electron-rich component, while the anthraquinone moiety serves as its electron-deficient counterpart. The strategic integration of these two moieties as essential building blocks in the formation of a donor-acceptor type Py-DQ-COF structure facilitates the efficient separation of electron-hole pairs. By employing benzylamine as a sacrificial reagent and utilizing water as the solvent, this study meticulously explores the photocatalytic efficiency in the production of H₂O₂. Mechanistic investigations validate that the reaction proceeds through a two-step two-electron (2e⁻) oxygen reduction reaction pathway, culminating in an impressive H₂O₂ yield of 15,207 µmol g⁻¹ h⁻¹, significantly exceeding the yields associated with conventional sacrificial alcohols. Cyclic experiments further elucidate that the materials exhibit commendable stability and sustain high activity. This study introduces a new method for the identification of novel sacrificial agents, and integrates anthraquinone into COFs, thereby offering an efficient strategy to optimize the industrial anthraquinone process for H₂O₂ production. Ultimately, it provides a valuable reference for the advancement of efficient and sustainable photocatalytic systems.