Óxidos de metais de transição mistos e seus nanocompósitos : síntese e aplicação em sistemas de armazenamento de energia

• Autor(a) principal: Aquino, Caroline Brambilla de
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: http://tede.mackenzie.br/jspui/handle/tede/4269
• topic: óxidos de metais de transição mistos; polímeros condutores; grafeno; supercapacitores; armazenamento de energia; CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

Searching to improve the performance of the energy storage devices through the development of novel nanomaterials and nanocomposites, in this work studied the synthesis, characterization and application of a mixed transition metal oxide, ruthenium tungstate (RuO2-WO3) and its nanocomposites, based on reduced graphene oxide (RuO2-WO3/rGO) and polyaniline (RuO2-WO3/PAni). For this, affordable and low-cost methodologies were used, obtaining the nanocomposite in two-steps, dividing between synthesis of the mixed transition metal oxide and then of the nanocomposite, through the physical mixing (RuO2-WO3/rGO) polymerization process (RuO2-WO3/PAni). In the first stage the synthesis of RuO2-WO3, produced in three different proportions between precursors of Ru:W, 1:10; 1:5; 1:2,5. Through several characterizations, there were evidence of the obtained nanostructure, verifying the formation of defects, changes in crystallinity, band gap, varied morphology with increasing proportion and high thermal stability. The electrochemical behavior of RuO2-WO3 thin films and device were analyzed, in which RuO2–WO3 showed a superior performance when compared with the control samples, WO3 and RuO2. The capacitance values of the film and the device were 661 mF cm-2 and 6.9 mF cm-2, respectively, being ninefold higher that capacitance values of the WO3 and RuO2. The high stability and easier diffusion processes of the RuO2-WO3 sample revealed that this material is promising to be applied as a supercapacitor. With the synthesis of the nanocomposites in turn, RuO2-WO3/rGO and RuO2-WO3/PAni, the characterizations indicated a great synergy, be the carbon derivates or conductive polymer. Due to these aspects, the solid devices prepared to obtain higher capacitance values of 12.9 mF cm-2 and 240 mF cm-2, respectively being these values 2 and 35 times higher than the control materials. These results reveal the potential application of RuO2-WO3, RuO2-WO3/rGO and RuO2-WO3/PAni materials to be applied to supercapacitor electrodes, in which the polyaniline-based nanocomposite already has a high capacity to replace the commercial systems used today.