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Abstract The growing interest in developing wearable energy storage devices requires the identification of suitable materials for the fabrication of their components. In this paper we report a new asymmetric fiber-shaped supercapacitor exploiting a composite of hematite and reduced graphene oxide aerogel obtained by a hydrothermal synthesis in presence of green extract as anode material and electrodeposited nanostructured MnO x as cathode. The three dimensional arrangement of the graphene flakes during the hydrothermal self-assembly process provides a highly conductive porous matrix with high surface area and, most importantly, a pores structure able to guarantee the rapid diffusion of the electrolyte ions and a fast electron transport. By simply modifying the hydrothermal recipe adding a dispersion of hematite nanoparticles, obtained using olive leaves extract as green surfactant, it is possible to obtain the decoration of the graphene network with the pseudocapacitive material. The resulting nanocomposite rGO/Fe 2 O 3 aerogel exhibits excellent pseudocapacitive behaviour and it is used, in combination with MnO x nanostructured electrode, to fabricate a flexible fiber-shaped device exhibiting superior rate capability and bending stability. The use of a green surfactant during the synthesis opens up new avenues for the fabrication of environmentally friendly electrodes for wearable energy storage applications. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Wearable wire-shaped supercapacitors were fabricated exploiting an innovative graphene aerogel self-assembly procedure on copper wire. The innovative aspect of the proposed procedure lies in the employment, for the first time to the best of our knowledge, of a hydrothermal graphene synthesis for an in situ coverage of a non-planar substrate. Specific capacitance per unit length was calculated to be about 12,5 mF/cm. The device can sustain repeated charge–discharge and bending cycles without suffering significant deterioration of specific capacitance. The combination of graphene aerogel self-coating method, flexibility and superior electrochemical performance makes the proposed device a suitable power source for e-textile applications. [ABSTRACT FROM AUTHOR]