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Master's Dissertation
DOI
10.11606/D.46.2009.tde-16092009-094433
Document
Author
Full name
Michele Aparecida Rocha
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Araki, Koiti (President)
Anaíssi, Fauze Jacó
Constantino, Vera Regina Leopoldo
Title in Portuguese
Síntese e propriedades de nanomateriais baseados em hidróxido de níquel obtidos pelo método sol-gel
Keywords in Portuguese
Eletroquímica
Hidróxido de níquel
Nanocompósitos
Nanopartículas
Sol-gel
Abstract in Portuguese
Hidróxido de níquel é um material amplamente estudado principalmente devido às suas aplicações como cátodo de baterias secundárias de níquel, entretanto tal sistema ainda apresenta problemas devido à progressiva diminuição da capacidade de carga em função do número de ciclos de oxidação/redução. No presente trabalho são descritas a preparação, caracterização e propriedades de nanomateriais de hidróxido de níquel, obtidos pelo processo sol-gel; e também dos nanocompósitos obtidos por meio da interação do sol de Ni(OH)2 com argilas catiônica (hectorita) e aniônica (HDL similar a hidrotalcita). Os materiais foram caracterizados por análise térmogravimétrica, espectroscopia UV-Vis e infravermelho, difração de raios-X, microscopia eletrônica de varredura, voltametria cíclica e microbalança eletroquímica a cristal de quartzo. Os resultados obtidos são claramente consistentes com a forma α-Ni(OH)2, e apresentam uma maior reversibilidade eletroquímica que os nanomateriais análogos preparados por outros métodos. Além disso, essa característica foi melhorada por meio de tratamento térmico a 240 °C, ou por meio da incorporação nas matrizes lamelares hospedeiras, gerando nanomateriais com grande potencialidade para o desenvolvimento de dispositivos eletroquímicos, em particular baterias, dispositivos eletrocrômicos, catalisadores e sensores amperométricos.
Title in English
Synthesis and properties of sol-gel nickel hydroxide nanomaterials
Keywords in English
Electrochemistry
Nanocomposites
Nanoparticles
Nickel hydroxide
Sol-gel
Abstract in English
Nickel hydroxide has been extensively studied because of its use as active material in the cathode of alkaline secondary batteries, but the main problem related to the progressive decrease of charge capacity as a function of the number of oxidation/reduction cycles still remains unsolved. In this work, the preparation, characterization and electrochemical properties of nickel hydroxide nanomaterials obtained by sol-gel method, and of nanocomposites materials prepared by the combination of nickel hydroxide sol and a cationic clay (hectorita) and an anionic clay (LDH like hydrotalcite) are described. The materials were characterized by thermogravimetric analyses, UV-Vis and IR spectroscopy, X-ray diffractometry, scanning electron microscopy, cyclic voltammetry and electrochemical quartz microbalance. The results were consistent with the α-Ni(OH)2 phase, but showing better electrochemical reversibility than that of similar materials obtained by others methods. Furthermore, this property was enhanced by thermal treatment at 240 °C or by Ni(OH)2 incorporation into the layered hosts. In conclusion nickel hydroxide nanomaterials with possible applications for the development of electrochemical devices such as batteries, electrochromic devices, catalysts and amperometric sensors were prepared and their exceptional electrochemical reversibility demonstrated
 
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ErrataMicheleARocha.pdf (410.04 Kbytes)
Publishing Date
2011-01-07
 
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