# Photochemical Aerobic Upcycling of Polystyrene Plastics via Indium Salt‐Mediated Synergistic Catalysis

## TL;DR

A new method uses light and a catalyst to convert polystyrene plastic waste into useful chemicals like benzoic acid under mild conditions.

## Contribution

A practical and efficient photochemical system for polystyrene upcycling using InBr3 and bromine radicals is introduced.

## Key findings

- The method efficiently depolymerizes polystyrene into benzoic acid under mild conditions.
- The system works on various polystyrene materials and scales up to 1 gram reactions.
- Value-added compounds of pharmaceutical and industrial interest can be produced.

## Abstract

The photochemical upcycling of polystyrene (PS) represents a sustainable method for the transformation of plastic waste into added‐value chemical feedstock. Herein, we propose a convenient and efficient photochemical catalytic system that integrates InBr3 catalysis with bromine radical sources, such as tosyl bromide and N‐bromosuccinimide (NBS). This approach enables the effective depolymerization of PS under mild conditions, providing benzoic acid in high yields. The protocol exhibited broad substrate tolerance, efficiently converting a variety of commercial and everyday PS‐based materials and was also successfully applied to a 1‐gram reaction. Comprehensive mechanistic investigations were performed, while applications to generate a series of value‐added compounds of potential pharmaceutical and industrial interest are highlighted. This study offers a practical method for the photochemical upcycling of PS waste through bromine radical‐mediated depolymerization.

This study presents a practical aerobic photochemical strategy for the upcycling of polystyrene waste, combining bromine radical mediation with InBr3 catalysis. The approach efficiently depolymerizes diverse PS materials under mild conditions, yielding benzoic acid and enabling downstream production of value‐added compounds.© 2026 WILEY‐VCH GmbH