Polyaniline is a remarkable conjugated polymer having valuable structural and physical characteristics. Nevertheless, polyaniline has poor solubility and structural durability which had limited its practical utilization. Consequently, polyaniline has been reinforced with carbonaceous and inorganic nanoparticles to enhance its processability and physical properties, such as electrical/thermal conductivity and thermal/mechanical stability. Accordingly, polyaniline has been applied as a valuable matrix material to form nanocomposites with graphene which is a one atom thick nanosheet of hexagonally arranged carbon atoms. Subsequently, graphene as well as modified graphene forms have been utilized as important nanoadditives for the polyaniline matrix. This state-of-the-art review article has been designed to investigate the fabrication, characteristics, and applications of the polyaniline and graphene/modified graphene based nanomaterials. Potential enhancements in the physical characteristics of the pristine polyaniline upon graphene reinforcement seemed to be reliant upon the matrix-nanofiller interactions, interface formation, and synergetic effects between polyaniline-graphene. Subsequently, practical aspects of the polyaniline/graphene nanocomposites have been discussed regarding their applications in the fields of solar cells, supercapacitors, and sensors. According to the literature analysis, dye sensitized solar cell based on polyaniline/graphene and polyaniline/graphene oxide exhibited superior power conversion efficiencies ∼2.0-7.6 % and open circuit voltage ∼500-800 mV. Supercapacitor electrodes based on polyaniline/graphene oxide and polyaniline/reduced graphene oxide showed significantly high values of specific capacitance and capacitance retention of ∼1100-1900 Fg−1 and ∼80-98 %, respectively, during >5000-6000 cycles. Besides, the polyaniline/graphene oxide depicted superior sensitivity and response time for gas sensors (∼20 % and 50 s, respectively) and humidity sensors (>90 % and 4-7 s, respectively) and low detection limits for biosensors.
