Photothermal Catalytic Recycling of Polyester Over Magnetic Ni-MnO_x Nanocatalyst

The solar-driven catalytic recycling of plastics has recently emerged as a new frontier in industry. Nevertheless, its large-scale application requires the catalysts being capable of the strong absorption of visible and near-infrared light, strengthened photothermal efficiency, high activity and selective toward target product, enhanced stability, as well as easy separation from the products. In this work, magnetic Ni-MnO_x nanocatalyst (MN/C) is synthesized via the pyrolysis of metal-organic framework (MOF) for the photothermal catalytic recycling of polyethylene terephthalate (PET) to bis(2-hydroxyethyl) terephthalate (BHET). Detailed investigations demonstrate that the strong interaction between MnO_x and Ni enables H₂ spill-over from Ni to Mn species and electron transfer from Mn to Ni, where MnO_x plays the active sites and Ni promotes the efficiency for photo-to-heat conversion, as a result of significantly enhanced photothermal catalytic performance. Consequently, PET is completely converted after photothermal recycling for 30 min (0.84 W cm^-2) at 190 °C, with a BHET selectivity of ≈79%. Moreover, MN/C has been successfully applied for recycling PET from various sources. In addition to the promising performance, the low-cost and easy magnetic separation of MN/C will further contribute to the sustainable recycling of plastics.