@PhDThesis{Sardinha:2022:PrCaCo,
author = "Sardinha, Andr{\'e} Ferreira",
title = "Produ{\c{c}}{\~a}o e caracteriza{\c{c}}{\~a}o de
comp{\'o}sitos bin{\'a}rios e tern{\'a}rios nanoestruturados de
fibra de carbono/{\'o}xido de grafeno/{\'o}xido de
n{\'{\i}}quel como eletrodos de alto desempenho em
supercapacitores",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2022",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2022-02-08",
keywords = "supercapacitores, eletroqu{\'{\i}}mica, {\'o}xido de grafeno,
{\'o}xido de n{\'{\i}}quel, comp{\'o}sitos, electrochemistry,
supercapacitors, graphene oxide, nickel oxide, composites.",
abstract = "{\'O}xido de n{\'{\i}}quel (NiO), derivados de grafeno e fibras
de carbono (FC) foram estudados sistematicamente visando a
produ{\c{c}}{\~a}o de comp{\'o}sitos para aplica{\c{c}}{\~a}o
como eletrodos em supercapacitores. A influ{\^e}ncia da
oxida{\c{c}}{\~a}o das FC em HNO3 foi avaliada pelas suas
respostas eletroqu{\'{\i}}micas e molhabilidade. A FC mais
oxidada mostrou um aumento de capacit{\^a}ncia de 1.625% em
compara{\c{c}}{\~a}o com a FC n{\~a}o oxidada. O {\'o}xido de
grafeno (OG) foi depositado sobre as FC por imers{\~a}o. Os
comp{\'o}sitos de {\'o}xido de grafeno/fibra de carbono tratada
por 30 minutos (OG/FC30) apresentou um aumento de
capacit{\^a}ncia de cerca de 8.250% em compara{\c{c}}{\~a}o com
o OG/FC. Depois, para avaliar a influ{\^e}ncia do grau de
oxida{\c{c}}{\~a}o sobre as propriedades do OG, foram realizadas
s{\'{\i}}nteses de OG variando a concentra{\c{c}}{\~a}o do
agente oxidante e observou-se que a quantidade de defeitos
aumentou em fun{\c{c}}{\~a}o do grau de oxida{\c{c}}{\~a}o e
que o tamanho do cristalito variou de 6,39 para 3,93 nm. O OG
menos oxidado apresentou maior perfil capacitivo devido {\`a}
menor quantidade de defeitos e {\`a} maior disponibilidade de
hidroxilas presentes na superf{\'{\i}}cie. Para
obten{\c{c}}{\~a}o do {\'o}xido de grafeno reduzido (OGR) sobre
as FC, os OG menos oxidados foram reduzidos por diferentes
m{\'e}todos e a redu{\c{c}}{\~a}o t{\'e}rmica apresentou as
melhores propriedades eletroqu{\'{\i}}micas. O comp{\'o}sito
hidr{\'o}xido de n{\'{\i}}quel/ {\'o}xido de grafeno
reduzido/fibra de carbono (Ni(OH)2/OGR/FC) foi sintetizado via
m{\'e}todo hidrotermal em 140 °C, 170 °C e 200 °C com singular
varia{\c{c}}{\~a}o morfol{\'o}gica entre as amostras e
ap{\'o}s a calcina{\c{c}}{\~a}o somente as amostras obtidas a
200 °C n{\~a}o sofreram delamina{\c{c}}{\~a}o. Na etapa final,
a convers{\~a}o de Ni(OH)2/OGR/FC em {\'o}xido de
n{\'{\i}}quel/ {\'o}xido de grafeno reduzido/fibra de carbono
(NiO/OGR/FC) foi estudada nas temperaturas de 300 °C, 400 °C e 500
°C. Neste intervalo, uma mudan{\c{c}}a no mecanismo de
armazenamento de energia dos eletrodos foi observada, onde os
tratados a 300 °C apresentaram comportamento t{\'{\i}}pico de
bateria enquanto os tratados a 500 °C apresentaram comportamento
t{\'{\i}}pico de supercapacitores. Como resultado a
capacit{\^a}ncia gravim{\'e}trica do eletrodo OGR/FC, que era de
94 F/g, aumentou para cerca de 769 F/g no eletrodo NiO/OGR/FC
tratado a 500 °C. Os testes de ciclabilidade indicaram que os
dispositivos apresentaram pouca estabilidade ap{\'o}s 2.350
ciclos quando submetidos {\`a} corrente de 500 \μA.
ABSTRACT: Nickel oxide (NiO), graphene derivatives, and carbon
fibers (CF) were systematically studied, aiming at the production
of composites for application as electrodes in supercapacitors. CF
oxidation influence in HNO3 was evaluated by its electrochemical
responses and wettability. The more oxidized CF showed a
capacitance increase of 1,625% compared to that of non-oxidized
CF. Graphene oxide (GO) was deposited on the CF by immersion
process. The graphene oxide/carbon fiber treated for 30 min
(GO/CF30) composites showed a capacitance increase of about 8,250%
compared to that of GO/CF. Then, to evaluate the influence of the
oxidation degree on the GO properties, GO syntheses were carried
out by varying the oxidizing agent concentration and it was
observed that the number of defects increased as a function of the
oxidation degree with the crystallite size variation from 6.39 to
3.93 nm. The lowest oxidized GO presented the highest capacitive
profile due to its smallest amount of defects associated to its
greatest surface hydroxyl availability. To obtain the reduced
graphene oxide (RGO) on the CF, the lowest oxidized GO was reduced
by different methods where the thermal reduction showed the best
electrochemical properties. The nickel hydroxide/reduced graphene
oxide/carbon fiber (Ni(OH)2/RGO/CF) composites was synthesized via
hydrothermal method at 140 °C, 170 °C and 200 °C with unique
morphological variation among the samples. After calcination only
the samples obtained at 200 °C did not present delamination.
Finally, the conversion of Ni(OH)2/RGO/CF into nickel
oxide/reduced graphene oxide/carbon fiber (NiO/RGO/CF) was studied
at temperatures of 300 °C, 400 °C and 500 °C. In this range, a
change in the energy storage mechanism of the electrodes was
observed, where those treated at 300 °C showed typical battery
behavior while those treated at 500 °C showed typical
supercapacitor behavior. As a result, the gravimetric capacitance
of the RGO/CF electrode of 94 F/g increased to 769 F/g for
NiO/RGO/CF electrode treated at 500 °C. In short, it can be
concluded that all stages of this work were optimized with a broad
study of the parameters for obtaining both the constituent
materials and the composites themselves. Cycling tests indicated
that the electrodes are unstable after 2,350 cycles when subjected
to 500 \μA.",
committee = "Ferreira, Neiden{\^e}i Gomes (presidente/orientadora) and Berni,
Luiz {\^A}ngelo and Corat, Evaldo Jos{\'e} and Gon{\c{c}}alves,
Emerson Sarmento and Almeida, Dalva Alves de Lima",
englishtitle = "Production and characterization of binary and ternary composites
nanostructured carbon fiber/graphene oxide/nickel oxide as high
performance electrodes in supercapacitors",
language = "pt",
pages = "140",
ibi = "8JMKD3MGP3W34T/46K5M6B",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/46K5M6B",
targetfile = "publicacao.pdf",
urlaccessdate = "05 maio 2024"
}