Non-emission hydrothermal low-temperature synthesis of carbon nanomaterials from poly (ethylene terephthalate) plastic waste for excellent supercapacitor applications

ABSTRACT Poly(ethylene terephthalate) (PET) has a wide range of applications that generate a lot of waste globally; thus, upcycling PET is important because it offers several industrial and economic advantages. This study describes a sustainable, emissions-free process for converting PET plastics into carbon nanomaterials (CNMs) named PT-nano powder. The thermal-hydrothermal method has employed the production of PT-nano powder above the glass transition temperature (Tg) of PET plastics. Under optimal conditions, PET plastics were efficiently converted into PT-nano powder with 86.6% crystallinity and an average particle size of 6.5 nm. The PT-nano powder was characterized for physical and chemical properties using different techniques, including UV-Vis, FTIR, Raman spectroscopy, XRD, FESEM, TEM, and proton NMR analysis. The characterization confirms the complete conversion of PET to solid fractions of carbon nanomaterial. The PT-nano powder was tested in supercapacitor performance application with electrochemical characterization. The symmetric fabrication showed a specific capacitance of 250.8 F/g, energy density of 34.83Wh/kg, and power density of 999.9W/kg with a current density of 0.5A/g. The device fabrication exhibited high cycle stability and high capacitance retention of 96.8% with a current density of 1.5A/g after 10000 cycles. GRAPHICAL ABSTRACT