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Publication
Fabrico de elétrodos de óxidos de ferro para armazenamento de energia
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Abstract(s)
As nanopartículas de magnetite e nanoplaquetas de magnetite e hematite foram
sintetizadas através do método de co-precipitação com o uso da amónia como agente alcalino
e também foi feito um tratamento térmico às nanopartículas de magnetite, a fim de as oxidar e
transformar em maghemite. A caracterização físico-química e a morfologia analisadas
indicaram que as partículas são cristalinas, sem impurezas e com um diâmetro médio de 12,4
nm para as nanopartículas de magnetite e um diâmetro de 31,3 nm para as nanoplaquetas de
magnetite e hematite. Foram estudados os elétrodos fabricados com as nanopartículas em
duas gamas de potencial, conseguindo-se valores de capacidade elétrica específica de 77,5
F/g para o elétrodo de magnetite, 43,14 F/g para o elétrodo de magnetite e hematite e de 42,36
F/g para o elétrodo de maghemite, na janela de potencial positivo, a uma velocidade de
varrimento de 10 mV/s. A densidade de carga obtida foi de 124,1 mC/cm2 para a magnetite,
62,12 mC/cm2 para a magnetite e hematite e 72,87 mC/cm2 para a maghemite, no potencial
positivo e no potencial negativo respetivamente. A influência da massa de óxido na capacidade
do elétrodo mostrou que o elétrodo se torna mais estável quando a sua massa é igual a 8 mg.
Nanoparticles of magnetite and nanoplates of magnetite and hematite were synthesized by the co-precipitation method with the use of ammonia as an alkaline agent and a thermal treatment was also made to the magnetite nanoparticles in order to oxidize and transform them into maghemite. The physicochemical characterization and morphology analyzed indicated that the particles are crystalline, with no impurities and with an average diameter of 12.4 nm for the nanoparticles of magnetite and a diameter of 31.3 nm for the nanoplates of magnetite and hematite. The electrodes manufactured with the nanoparticles were studied in two potential ranges, obtaining specific capacitance values of 77.5 F/g for the magnetite electrode, 43.14 F/g for the magnetite and hematite electrode and 42.36 F/g for the maghemite electrode in the positive potential window at a scanning rate 10 mV/s. The obtained charge density was 124.1 mC/cm2 for magnetite, 62.12 mC/cm2 for magnetite and hematite and 72.87 mC/cm2 for magnetite, at positive potential and negative potential respectively. The influence of the oxide mass on the electrode capacitance showed that the electrode becomes more stable when its mass is equal than 8 mg.
Nanoparticles of magnetite and nanoplates of magnetite and hematite were synthesized by the co-precipitation method with the use of ammonia as an alkaline agent and a thermal treatment was also made to the magnetite nanoparticles in order to oxidize and transform them into maghemite. The physicochemical characterization and morphology analyzed indicated that the particles are crystalline, with no impurities and with an average diameter of 12.4 nm for the nanoparticles of magnetite and a diameter of 31.3 nm for the nanoplates of magnetite and hematite. The electrodes manufactured with the nanoparticles were studied in two potential ranges, obtaining specific capacitance values of 77.5 F/g for the magnetite electrode, 43.14 F/g for the magnetite and hematite electrode and 42.36 F/g for the maghemite electrode in the positive potential window at a scanning rate 10 mV/s. The obtained charge density was 124.1 mC/cm2 for magnetite, 62.12 mC/cm2 for magnetite and hematite and 72.87 mC/cm2 for magnetite, at positive potential and negative potential respectively. The influence of the oxide mass on the electrode capacitance showed that the electrode becomes more stable when its mass is equal than 8 mg.
Description
Dissertação submetida como requisito parcial para
obtenção do grau de Mestre em Engenharia de
Produção
Keywords
Óxidos de ferro Magnetite Hematite Maghemite Nanopartículas Elétrodo Iron oxide Nanoparticles Electrode