Photothermal Oxidative Upcycling of Polyethylene to Aliphatic Dicarboxylic Acids over a Pt/TiO ₂ Catalyst

Plastic pollution poses a significant global environmental challenge, and the chemical upcycling of polyethylene (PE) into high-value products under mild conditions remains a critical goal. Here, we report a one-step photothermal catalytic process for the oxidative upcycling of PE to aliphatic dicarboxylic acids (C4–C31) using a Pt/TiO2 catalyst and water as the reaction medium. Operating at 130 °C (near the melting point of PE), 65 mW/cm2 illumination and 1.5 MPa air pressure, this method achieves 88 wt % of oil/feedstock within 16 h. In addition, optimized conditions (160 °C, 370 mW/cm2) enable an 84 wt % oil/LDPE yield within just 1.5 h. Mechanistic investigations indicate that superoxide radicals (O2•–) are pivotal in mediating selective C–C bond cleavage and oxidation, while the ultralow Pt loading (0.08 wt %) significantly promotes charge carrier separation. The process demonstrates good scalability, compatibility with postconsumer PE, and catalyst reusability, offering an effective approach to transform plastic waste into valuable chemical feedstocks. These results highlight the potential of photothermal catalysis for the upcycling of plastic waste into oxygen-containing chemical products.