Upcycling Waste Polyethylene into Carbon Nanomaterial via a Carbon-Grown-on-Carbon Strategy.

Upcycling waste plastics (e.g., polyethylene (PE)) into value-added carbon products is regarded as a promising approach to address the increasingly serious waste plastic pollution and simultaneously achieve carbon neutrality. However, developing new carbonization technology routes to promote the oxidation of PE at low temperature and construct the stable cross-linking network remains challenging. Here, a facile carbon-grown-on-carbon strategy is proposed using carbon black (CB) to convert waste PE into core/shell carbon nanoparticles (CN) in high yields at low temperature. The yield of CN remarkably increases when the heating temperature decreases or the dosage of CB increases. The obtained CN displays turbostratic structure and closely aggregated granular morphology with a size of ≈80 nm. It is found that, prior to the oxidation and carbonization of PE, CB forms a 3D network architecture in the PE matrix. More importantly, CB not only catalyzes the partial oxidation of PE to form PE macromolecular radicals and introduce oxygen-containing groups at low temperature in the early stage, but also favors for the construction of a stable cross-linking network in the latter stage. This work offers a facile sustainable strategy for chemical upcycling of PE into value-added carbon products without post-treatments or usage of metallic catalysts.