Metal-free photocatalytic transformation of waste polystyrene into valuable chemicals: advancing sustainability through circular economy

Abstract

Abstract: The present study offers a metal-free photocatalytic visible-light-driven protocol for addressing the plastic waste crisis. The reaction uses photocatalytic C–H bond activation to deconstruct polystyrene (PS) waste into valuable products under ambient conditions (1 bar O2, 250 W Hg lamp) in an ethyl acetate/acetonitrile solvent system. The high surface area metal-free photocatalyst was synthesised using flow-assisted exfoliation and demonstrated high selectivity for acetophenone and PS conversion in sunlight. The study presents a promising and sustainable approach to combat plastic pollution by introducing the concept of visible light photocatalysis for polymer deconstruction. The technology offers a simple, reproducible, eco-friendly method that could significantly contribute to a circular economy to produce wealth (chemicals) from waste. Detailed characterisations, control experiments, and scavenging studies have been conducted to propose the mechanism of PS upcycling to acetophenone and benzoic acid. The photocatalytic C–H activation showcased in this study could motivate material scientists and catalysis researchers to create uncomplicated, metal-free photocatalysts that can activate other bonds with high dissociation energy, leading to the formation of crucial synthetic intermediates of industrial significance. This technology represents a crucial step towards more efficient and sustainable methods for combatting plastic pollution, highlighting the potential of green chemistry for creating sustainable solutions to environmental challenges.