Enhancing Photocatalytic Activity of Porous Organic Frameworks via Facile Post-Synthetic Modification for Ultrafast Uranium Extraction

Abstract

The design of heterogeneous photocatalysts, especially those utilizing advanced porous organic frameworks, has recently attracted considerable interest for their ability to efficiently convert solar energy into chemical energy by harnessing water as a sustainable electron source. However, the skeleton design for efficient porous-organic-photocatalysts relies too heavily on pre-synthetic strategies, which typically involve either selecting photoactive-linkers or incorporating donor-acceptor moieties into the system through pre-synthetic construction approach. In this regard, to advance the development of efficient functional heterogeneous-organic-photocatalysts, we present a metal-free, cost-effective, facile post-synthetic approach to enhance the photocatalytic activity of porous organic frameworks. In this work, we decoded the post-synthetic sulfonation reaction as a strategically chosen, facile post-synthetic tool to enhance the photocatalytic activity of porous organic frameworks by tuning the donor/acceptor ratio. To demonstrate this, a chemically robust, flexible ether-linked triazine framework is selected, and its potential photocatalytic activity is harnessed by implementing this post-synthetic sulfonation reaction. Thereafter, the significantly improved photocatalytic activity of the framework is strategically utilized in conducting photocatalytic uranium extraction. After the sulfonation, the simultaneous creation of an uranium-specific nanotrap along with enhanced photocatalytic activity makes the framework efficient for ultrafast uranium-photoreduction, offering a superior heterogeneous platform for photocatalytic uranium-extraction from groundwater and wastewater.