Facile synthesis of bromine-modified imine-based covalent organic frameworks for accelerated photocatalytic hydrogen peroxide production.

Abstract

Covalent organic frameworks (COFs) have attracted increasing attention as a new generation of photocatalytic platforms for hydrogen peroxide (H2O2) synthesis, benefiting from their precisely tailorable network architectures and outstanding optoelectronic characteristics. However, the traditional sealed-tube method for synthesis of imine-linked COFs suffers from harsh reaction conditions, high cost, low yield, and complex procedures, severely limiting their practical application. Nevertheless, the practical photocatalytic efficiency of COFs is often limited by inefficient charge separation and carrier migration. To overcome this limitation, a green and sustainable synthetic route was developed to produce two brominated imine-linked COFs on a gram scale. The resulting materials were subsequently evaluated as photocatalysts for H2O2 production. By introducing and regulating bromine-based functional moieties within the intrinsic nanoporous channels, the electronic configuration and light-harvesting capability of COFs frameworks can be precisely optimized. Such structural modulation facilitates efficient charge separation and migration, ultimately contributing to improved photocatalytic activity. Benefiting from the distinctive framework characteristics and superior optoelectronic features, the bromine-functionalized COFs demonstrate remarkable H2O2 generation efficiency, achieving a rate of 894.91 μmol·g-1·h-1 without the addition of sacrificial agents. Moreover, these materials retain excellent durability and regeneration capability during repeated catalytic cycles. This study offers valuable insights into the construction of imine-linked COFs-based photocatalysts and provides a promising design strategy for developing highly efficient platforms toward sustainable H2O2 synthesis.