Dynamic Self‐Focusing Photothermal Localization Induced Mild Solvent‐Free Upcycling of Polystyrene

Abstract

ABSTRACT The pervasive accumulation of nondegradable plastic waste, particularly microplastics, represents a critical environmental crisis demanding advanced recycling strategies. Here, we introduce a fully green, photo‐driven process for polystyrene (PS) upcycling, enabled by a synergistic thermal‐focusing and space‐confined catalysis. Using earth‐abundant MoO 3‐x , it can efficiently absorb sunlight to generate localized heat, dynamically melting adjacent PS and spontaneously forming a core‐shell MoO 3‐x @PS structure. Critically, the intrinsically low thermal conductivity of PS creates a self‐forming insulating layer, which traps thermal energy at the catalyst‐polymer interface. This self‐focusing thermal localization effect sustains a microscopic high‐temperature reaction zone under ambient conditions, dramatically enhancing energy efficiency. The concentrated heat cleaves inert C─C bonds, while photogenerated charge carriers facilitate selective oxidative degradation. Consequently, we achieve 75.0% PS conversion with 70.5% combined yield of valuable products, predominantly benzoic acid crystals that spontaneously separate post‐reaction. Operating without solvents or external heating, our strategy transforms waste PS into valuable chemicals using only sunlight. This work establishes a new paradigm for solid‐state photothermal upcycling, leveraging interfacial thermal localization to enable a truly sustainable light‐to‐chemicals circular path.