Development of nitrogen and phosphorus dual-doped reduced graphene oxide from waste plastic for supercapacitor applications: Comparative electrochemical performance in different electrolytes

Abstract

The persistent non-biodegradable nature of plastic highlights the urgent need for effective waste management and resource conservation, underscoring the crucial importance of recycling and upcycling within a cradle-to-cradle framework. This research introduces an eco-friendly and straightforward upcycling process for plastic waste, which produces significant quantities of reduced graphene oxide through a carefully designed 2-stage pyrolysis method. To enhance the electrochemical properties of the reduced graphene oxide, they were doped with heteroatoms (i.e. nitrogen and phosphorus) via a hydrothermal route. Also, as the nature of the electrolyte plays a significant role in electrochemical analysis, a comparative evaluation of the supercapacitive performance of the heteroatom-doped reduced graphene oxide was conducted across various aqueous electrolytes, including 1 M H₂SO₄, 6 M KOH, and 2 M KCl, as well as hydrogel polymer electrolytes such as 1 M H₂SO₄/1 M PVA, 2 M KCl/1 M PVA, and 6 M KOH/1 M PVA. Our results demonstrate that synthesized material from waste plastic exhibits excellent performance, particularly when combined with a 1 M H₂SO₄ electrolyte, achieving the highest specific capacitance of 407.6 F/g. In conclusion, this study presents a cost-effective and sustainable approach to promoting a circular economy by repurposing waste plastic for energy storage applications.