3D sponge nitrogen doped graphene (NG) was prepared economically from waste polyethylene-terephthalate (PET) bottles mixed with urea at different temperatures using green approach via a novel one-step method. The effect of temperature and the amount of urea on the formation of NG was investigated. Cyclic voltammetry and impedance spectroscopy measurements, revealed that nitrogen fixation, which affects the structure and morphology of prepared materials improve the charge propagation and ion diffusion. The prepared materials show outstanding performance as a supercapacitor electrode material, with the specific capacitance going up to 405 F g⁻¹ at 1 A g⁻¹. An energy density of 68.1 W h kg⁻¹ and a high maximum power density of 558.5 W kg⁻¹ in 6 M KOH electrolytes were recorded for the optimum sample. The NG samples showed an appropriate cyclic stability with capacitance retention of 87.7% after 5000 cycles at 4 A g⁻¹ with high charge/discharge duration. Thus, the prepared NG herein is considered to be promising, cheap material used in energy storage applications and the method used is cost-effective and environmentally friendly method for mass production of NG in addition to opening up opportunities to process waste materials for a wide range of applications.

Nowadays our planet suffers from an accumulation of plastic products that have the potential to cause great harm to the environment in the form of air, water, and land pollution. Plastic water bottles have become a great problem in the environment because of the large numbers consumed throughout the world. Certain types of plastic bottles can be recycled but most of them are not. This paper describes an economical solvent-free process that converts polyethylene terephthalate (PET) bottles waste into carbon nanostructure materials via thermal dissociation in a closed system under autogenic pressure together with additives and/or catalyst, which can act as cluster nuclei for carbon nanostructure materials such as fullerenes and carbon nanotubes. This research succeeded in producing and controlling the microstructure of various forms of carbon nanoparticles from the PET waste by optimizing the preparation parameters in terms of time, additives, and amounts of catalyst. Implications: Plastic water bottles are becoming a growing segment of the municipal solid waste stream in the world; some are recycled but many are left in landfill sites. Recycling PET bottles waste can positively impact the environment in several ways: for instance, reduced waste, resource conservation, energy conservation, reduced greenhouse gas emissions, and decreasing the amount of pollution in air and water sources. The main novelty of the present work is based on the acquisition of high-value carbon-based nanomaterials from PET waste by a simple solvent-free chemical technique. Thus, the prepared materials are considered to be promising, cheap, eco-friendly materials that may find use in different applications.