Conjugated Polymer Hydrogel Photocatalysts with Expandable Photoactive Sites in Water

Abstract

Water compatibility of heterogeneous photocatalytic materials is recently realized by utilizing hydrogels as a support; however, the embedment of photocatalysts in the hydrogels may hinder the photocatalytic activity and the regeneration of materials. Therefore, combining hydrophilicity and high accessibility to the active sites of heterogeneous photocatalysts is highly challenging. Herein, we report the design of a conjugated polymer hydrogel photocatalyst via complexation between a photoactive conjugated polymer with cationic side chains and a poly(acrylic acid) as polyanion. In water, the conjugated polymer hydrogel photocatalyst exhibited an enormous volumetric increase by swelling, which creates more accessible photoactive sites through the simultaneous expansion of the conjugated polymer chain. A simple solvent switch allows the reversible swelling of the hydrogel photocatalyst for recycling. The significantly enhanced photocatalytic activity of the hydrogel photocatalyst was demonstrated by the photodegradation of organic dyes and the formation of the enzyme cofactor nicotinamide adenine dinucleotide via photo-oxidation in water. Furthermore, the translucent and voluminous hydrogel photocatalyst was suitable to pack a large-scale flow column photoreactor for the rapid photocatalytic reactions.