Templating of catalytic gold and silver nanoparticles by waste plastic PET-derived hydrogel playing a dual role of a reductant and a matrix

The progressive accumulation of discarded plastic in the environment demands further development of waste management of plastic waste and conversion technologies of such waste to value-added materials. Recently, the conversion of plastic waste to functional materials via chemical recycling has attracted considerable attention. In this report, plastic waste (PET) was utilized for the preparation of a hydrogel-based catalyst via a cross-linking reaction of PET-derived oligo(terephthalamide)s followed by the electroless metallization. The polymeric matrix of PET-derived hydrogel plays multiple roles of (i) an adsorption media for noble metal ions such as Au3+ and Ag+, (ii) a reducing agent of Au3+ and Ag+ ions to Au0 and Ag0, and (iii) a matrix for the controlled growth of Au and Ag nanoparticles (AuNPs and AgNPs). The obtained hybrid hydrogels after metallization contained well -dispersed AuNPs and AgNPs of 6.1 +/- 3.7 nm or 6.1 +/- 1.4 nm size, respectively. The catalytic activities of the hybrid hydrogels with metal nanoparticles were studied in a model system of p-nitrophenol reduction in an aqueous solution. The hybrid materials of both Au@hydrogel and Ag@hydrogel were catalytically active for the reduction of p-nitrophenol, obeying the first-order kinetics. Importantly, the AuNPs or AgNPs in the hydrogel matrix preserved the original catalytic activity after multiple p-nitrophenol reduction reactions, showing a promising reusability of the catalysts. The proposed here approach aims to broaden the scope of conversion routes of plastic waste to value-added materials as well as to develop new types of polymeric matrices for templating and growth of metal nanoparticles for catalytic applications.

Automated summary

This study utilized discarded plastic to prepare a hydrogel-based catalyst through a cross-linking reaction and electroless metallization. The resulting hybrid hydrogels contained well-dispersed gold and silver nanoparticles, which exhibited catalytic activity for the reduction of p-nitrophenol and could be reused multiple times. This approach broadens the conversion routes of plastic waste and develops new types of polymeric matrices for templating and growth of metal nanoparticles.