Filmes nanoestruturados contendo grafeno e óxidos metálicos para estudo em dispositivos supercapacitores

Abstract

Research involving new nanocomposites is essential to reach supercapacitors with improved performance for energy storage. Carbon materials and metal oxides were used together to achieve supercapacitors with improved properties. In this work, approaches are presented for the application of nanostructured films using the Layer-byLayer (LbL) technique containing metal oxide nanostructures such as MnO2, ZnO and PdO, incorporated in reduced graphene oxide (rGO) sheets and arranged with polyalylamine hydrochloride (PAH) on an ITO (Indium tin oxide) substrate for study in supercapacitors. Spectroscopy in the ultraviolet visible (UV-VIS) region indicates the growth of the films, while field emission gun scanning electron microscopy (FEG-SEM) images confirm the incorporation of metal oxide nanostructures between the rGO layers and on the surface, while cyclic voltammetry (CV) measurements and galvanostatic charge discharge reveal the electrocapacitive properties of films. The highest values of capacitance obtained were 112 mF/cm2 and 460 F/g, 19 mF/cm² and 137 F/g, 26 mF/cm² and 1650 F/g, 3.4 mF/cm² and 50 F/g, for PAH/rGO-MnO2, PAH/rGO-ZnO, PAH/rGOMnO2-ZnO and PAH/rGO-PdO architecture systems, respectively, at a current of 4.85x10-6 A and 1 mV/s. All systems showed high performance of capacitive retention with losses less than 1% during 10,000 cycles of charge and discharge. These results demonstrate that the investigated films have favorable properties to be exploited in nanostructured energy storage systems.