Catalytic fabrication of graphene, carbon spheres, and carbon nanotubes from plastic waste

In this study, we reported sustainable and economical upcycling methods for utilizing plastics such as polyethylene terephthalate (PET) and polypropylene (PP) compiled from the garbage of a residential area as cheap precursors for the production of high-value carbon materials such as graphene (G), carbon spheres (CS), and carbon nanotubes (CNTs) using different thermal treatment techniques. Graphene, carbon spheres, and carbon nanotubes were successfully synthesized from PET, PP, and PET, respectively via catalytic pyrolysis. XRD and FTIR analyses were conducted on the three materials, confirming the formation of carbon and their graphitic structure. TEM images displayed uniform and consistent morphological structures of the fabricated materials. EDX data confirmed that the prepared carbon-based materials only contained carbon and oxygen without any significant contaminations. XPS results revealed significant peaks in the C 1s spectra associated with sp² and sp³ hybridized carbon for the three materials. BET spectra showed that the prepared CNTs (54.872 m² g^-1) have the highest surface area followed by carbon spheres (54.807 m² g^-1). The thermal stability of graphene surpassed both carbon spheres and carbon nanotubes which is mainly attributed to the stronger inter-molecular bonds of graphene. Based on the characterization of the prepared materials, these materials are promising to be utilized in environmental remediation applications due to their high carbon content, low cost, and high surface area.