3D-Printed COF/Zeolite Composites for Augmented Photocatalytic Hydrogen Peroxide Production

Abstract

Covalent Organic Frameworks (COFs), characterized by high porosity and fine-tuned structures, are promising photocatalysts for hydrogen peroxide (H2O2) production. However, their hydrophobic nature restricts the mass transfer in water, presenting challenges in achieving high performance. Coupling COFs with hydrophilic zeolites can potentially advance H2O2 production, yet integrating these two distinct types of porous materials is challenging. Herein, we first applied three-dimensional (3D) printing technology to fabricate COF/zeolite composite catalysts, which enabled superior photosynthesis of H2O2. By precisely optimizing binders and pre-polymerization conditions, homogeneous inks composed of zeolite nanocrystals and initial polymeric precursors were prepared with appropriate rheology for 3D printing. The resultant monolith with honeycomb-like open-channels was favorable for the in-situ growth and crystallization of COF by facilitating the efficient molecular transfer of condensing agents and large covalent segments during solvothermal post-treatment. Mechanistic studies indicated that introducing zeolites enhanced the hydrophilicity and O2 affinity within the composite, favoring the oxygen reduction reaction pathway. Consequently, the photosynthesis of H2O2 by the COF/zeolite composite was markedly improved by 52% compared to the bare COFs. This work provides a facile way to integrate COFs and zeolites by 3D printing, which may open diverse applications of such composites by taking advantage of both merits.