Recent progress in photothermal catalytic upcycling of waste plastics

As global plastic production continues to rise， the quantity of plastic waste has also increased dramatically. Effectively addressing plastic pollution while achieving the resource recovery and recycling of plastic waste has become a global challenge. Compared with conventional recycling methods， the photothermal catalysis process， which integrates photocatalysis and thermocatalysis， offers significant advantages such as high conversion efficiency and mild reaction conditions. Herein， this review outlines the research progress of photothermal catalysis technology in the treatment and resource recovery of plastic waste. It first elaborates on the mechanism of photothermal conversion， including plasmonic localized heating， non-radiative relaxation of semiconductors， and molecular thermal vibration. Based on the roles of light and heat in photothermal catalytic reactions， photothermal catalysis is classified into three categories： thermal-assisted photocatalysis， photo-driven thermocatalysis， and photo-thermal co-catalysis. The type of catalytic material plays a crucial role in regulating catalytic performance during the photothermal catalytic conversion of plastics. This review summarizes the catalytic properties of three typical photothermal catalytic materials： plasmonic metal nanoparticles， metal oxide semiconductors， and carbon-based materials， providing material design directions for efficient plastic upcycling. Furthermore， starting with the upcycling mechanisms of two representative plastics， polyethylene and polyester， the review summarizes the reaction pathways for plastic upcycling to produce liquid fuels and organic acids. Finally， based on the current research status， this review also highlights the technical challenges of using photothermal catalysis for plastic upcycling. This review aims to provide technical support for the chemical recycling of plastic waste and offer new perspectives for its upcycling.