The recent rapid growth in graphene-based supercapacitors has reached the point where there is a need for solid-state devices with physical flexibility, which will be a crucial advantage in modern electronic devices. Herein, we summarize recent developments toward an all solidstate graphene-based flexible supercapacitor. The routes to produce graphene-based electrode materials, along with the typical fabrication techniques for flexible devices, are thoroughly discussed. Furthermore, the structural morphology of the electrode materials is closely related to the electrochemical performance, and the influence of the electrode components on the mechanical flexibility of the fabricated devices is examined. Lastly, a summary of the overall electrochemical properties and current development of the reported devices is presented progressively to predict the future trends toward the realization of an ultimate-performance graphene-based flexible supercapacitor.

Polyaniline (PANI) is a famous conductive polymer, and it has received tremendous consideration from researchers in the field of nanotechnology for the improvement of sensors, optoelectronic devices, and photonic devices. PANI is doped easily by different acids and dopants because of its easy synthesis and remarkable environmental stability. This review focuses on different preparation processes of PANI thin film by chemical and physical methods. Several features of PANI thin films, such as their magnetic, redox, and antioxidant, anti-corrosion, and electrical and sensing properties, are discussed in this review. PANI is a highly conductive polymer. Given its unique properties, easy synthesis, low cost, and high environmental stability in various applications such as electronics, drugs, and anti-corrosion materials, it has attracted extensive attention. The most important PANI applications are briefly reviewed at the end of this review.

Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ∼100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 µm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 µm and ∼8000 µm 2 , respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.

17This paper essentially reviews the types of graphene-based nanofillers and the fabrication of 18 graphene/polymer nanocomposites. Routes to produce the graphene materials, along with the 19 methods and modifications used to efficiently disperse the graphene nanofillers within the 20 polymer matrices are discussed. In addition, the mechanical properties, morphological, 21 structural, electrical conductivities, electrochemical activities, thermal stabilities, and gas 22 barrier properties are evaluated, along with the direct relationships of these properties with 23 the graphene-polymer interaction and their dispersion in the polymer matrix. Finally, a brief 24 summary of the practical applications of polymeric-graphene materials along with the current 25

Dopamine (DA) is an important catecholamine neurotransmitter in the mammalian central nervous system that influences several physiological functions. The impact of DA levels within the human body significantly affects the body functions. Maintaining DA level is essential and the electrochemical detection methods are often used to detect the DA level to regulate the body function. In this review, graphene (functionalized graphene and N-doped graphene) and its composites (metal, metal oxide, polymer, carbonaceous materials, clay, zeolite, and metal-organic framework based graphene composites) modified electrodes with their improved sensing performance towards DA along with several interfering species are described. Further, recent developments on the fabrication of various graphene based composite modified electrodes are also presented. Some important strategies to improve the selectivity and sensitivity towards DA with graphene based composite modified electrodes are also described.