Physical exfoliation of graphene and molybdenum disulfide sheets using conductive polyaniline: an efficient route for synthesizing unique, random-layered 3D ternary electrode materials

Abstract

Vertically random-layered three-dimensional ternary nanohybrids were synthesized by combining graphene, molybdenum disulfide (MoS₂), and polyaniline (PANI) via a simple physical exfoliation process. During this process, PANI penetrates the interlayers of bulk MoS₂ without the requirement for any additional chemical treatment, effectively dispersing MoS₂ layers in the liquid phase. In addition, graphene, with several functional groups on its surface, and PANI convert the semiconducting trigonal prismatic phase of MoS₂ to a metallic octahedrally coordinated phase, thereby enhancing the electrical conductivity. Moreover, the obtained nanohybrid has an open porous structure that facilitates electrolyte-mediated ion and charge transfer, which increases the effective surface area for electrochemical reactions and charge storage. The effect of different graphene, MoS₂, and PANI contents on the electrical/electrochemical properties of the nanohybrids was investigated, and the optimal composition for the use of the nanohybrid as an electrode material was determined. Notably, the nanohybrid with a nominal graphene/MoS₂/PANI weight ratio of 1 : 1 : 80 exhibited excellent electrochemical properties, exemplified by the prominent redox reaction, low charge transfer resistance, and high specific capacitance. Flexible all-solid-state capacitor cells employing the nanohybrid achieved a maximum capacitance of 162 F g⁻¹, good flexibility, and good long-term cycling stability in two different electrolytes, i.e., acidic and neutral solution.