Interfacial self-assembly of preformed colloidal nanocatalysts for pyrolysis upcycling of waste plastic

Abstract

Catalytic pyrolysis of waste plastics offers a sustainable approach to transform plastic waste into valuable carbon nanomaterials such as carbon nanotubes. Conventional methods for catalyst preparation provides limited control over catalyst morphology and loading. In addition, the powder catalysts remain entangled with the product carbonaceous materials and are difficult to separate. To mitigate these challenges, here, we present the first example of an interfacial self-assembly based approach for the construction of bulk catalysts with well-defined nanoscale morphologies for catalytic pyrolysis. The versatility of the self-assembly approach allowed us to deposit model Fe₃O₄ catalyst nanoparticles onto various types of supporting materials (S304, Ni, Ti, and Cu) to systematically investigate their impact on catalytic efficiency. Our studied revealed that CNT formation is influenced significantly by substrate-introduced effects. Among the tested supports, S304 system offered the highest selectivity for CNT growth, giving a carbon yield with a value of 207 mg/g plastic. While Ni and Ti generated more carbon products but with lower CNT mass ratio. Importantly, the self-assembled catalyst system also enables facile separation of carbon products from the support, offering a practical advantage over conventional powder-based systems. More broadly, our approach provides a versatile platform for designing robust and efficient catalysts with potential applications beyond plastic upcycling.