Exploring graphene's impact on graphite/PANI matrix composites: high-pressure fabrication and enhanced thermal-electrical properties

Abstract

This study investigates the effects of the graphene content and applied pressure on the electrical and thermal conductivities of graphite/polyaniline (GP) and graphite/graphene/polyaniline (GGP) composites produced via direct mixing method. Based on the electrical and thermal conductivity results, 14 wt% graphene content was found to be the crucial threshold, beyond which extra graphene additions exhibited different behaviors in pressed and unpressed samples. While the electrical conductivity of the unpressed samples increased up to 14 wt% graphene addition, the thermal conductivity increased further after 14 wt% graphene addition. The addition of graphene induced notable changes in the electronic configurations of quinoid and benzenoid rings, as evidenced by ATR-FT-IR spectroscopy. Based on XPS data, the addition of graphene to the graphite/PANI-CSA matrix affected the electronic distribution and charge transfer mechanisms within the GGP composites, particularly showing the impact of graphene addition on the electronic structure of PANI-CSA in the GGP-14 527 MPa sample. Importantly, the interlocking of graphene and graphite layers observed in the GGP-14 sample pressed at 527 MPa (according to Raman and XRD data) led to enhanced thermal (2253 W m⁻¹ K⁻¹) and electrical (210 S cm⁻¹) conductivity. The interlocked configuration of graphene and graphite in GGP-14 527 MPa facilitated efficient electron and phonon flow throughout the hexagonal CC rings and partially charged nitrogen and oxygen atoms of PANI-CSA. In future work, the concept of interlocked graphene and graphite layers can be used to further enhance the thermal and electrical properties in thermoelectric material applications.