An Integrated Plasma-Photocatalytic System for Upcycling of Polyolefin Plastics

Nondegradable polyolefin plastics, which account for >60 % of total plastic waste, trigger severe global concerns and thus demand effective management technologies. However, owing to the chemical inertness of non-polar C-C backbones in the polyolefin structure, efficient upcycling of polyolefin plastics under ambient conditions remains a great challenge. This study introduces an integrated plasma-photocatalytic technology, coupling plasma treatment with solar-driven reforming under mild conditions, for the efficient upcycling of polyolefin plastics into value-added hydrogen and gaseous fuels. The first plasma step grafts oxygenated groups, such as -OH, O-C=O, and C=O, onto the polyolefin chains, which leads to the formation of a polar and hydrophilic polymer that facilitates the subsequent reforming in the photocatalytic step. Therefore, high hydrogen production activity with a benchmark efficiency of >100 μmol g^-1  h^-1 was achieved. Moreover, the integrated process also demonstrates high versatility in upcycling different polyolefin plastics including polyethylene, polypropylene and polyvinyl chloride. The findings provide a new avenue for plastic upcycling in an efficient and sustainable way.