Copper-catalyzed plastic waste synthesized graphene nanosheets/polypyrrole nanocomposites for efficient thermoelectric applications

Presently, various catalysts have been reported for the synthesis of carbon nanomaterials from a variety of plastic waste, which needs to be removed at the end of the synthesis process by using chemical techniques and hence make the process more typical from the aspect of cost-benefit and circular economic aspects. Herewith, we report copper turnings as the cost-effective and greener catalytic templates for synthesizing highly conducting graphene nanosheets (GNs). The synthesis of the GNs from plastic waste was done as we previously reported in the steps of the pyrolytic process, where the copper turnings are used as catalytic templates in the present study. Because of the excellent catalytic efficiency towards breaking old carbon-carbon bonds and forming new carbon-carbon bonds, the copper turnings act as an excellent degradation catalyst and promote the growth of graphitic skeletons and, consequently, graphene nanosheets. The synthesized GNs showed a high conductivity of ∼ 1730 S/m. GNs thus synthesized is implemented for synthesizing GNs/polypyrrole nanocomposites, which is later investigated for the TE applications. The values of the Seebeck coefficient showed that the composite of GNs/polypyrrole performs as a p-type semiconductor. The TE figure of merit (ZT) for GNs/polypyrrole demonstrated good thermoelectric characteristics and showed a value of 3.75 × 10⁻⁶ at the temperature. Thus, the present method of synthesis of GNs showed a more convenient, industrial friendly technique for the production of plastic waste derived graphene nanosheets and its application for thermal energy conversion applications.