masterThesis
Síntese e caracterização de nanofios de óxido de cobre produzidos por termo-oxidação
Fecha
2020-08-28Registro en:
AMORIM, Allan Miguel Franco de. Síntese e caracterização de nanofios de óxido de cobre produzidos por termo-oxidação. 2020. 108f. Dissertação (Mestrado em Engenharia Química) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2020.
Autor
Amorim, Allan Miguel Franco de
Resumen
The study of the development of nanostructured semiconductor materials is
responsible for a considerable portion of tectonological advances in recent years. Nanowires, in
particular, offer unique opportunities to control electronic and optical properties in
semiconductors. In this context, the present work investigated the formation of copper oxide
nanowires through the oxidation process of metallic copper sheets and how the synthesis
conditions influence the concentration and structure of the oxides. For that, X-ray diffraction
(XRD) and scanning electron microscopy (SEM) characterizations were performed. The nanowire
synthesis process was first evaluated in the treatment of metallic copper sheets before the oxidation
process and then in the thermal process performed in atmospheric environment. Two treatment
procedures were investigated, namely: immersion in chloridric acid solution followed by
immersion in ethanol in ultrasound; and immersion in acetone followed by immersion in isopropyl
alcohol in ultrasound. It is concluded that the treatment with hydrochloric acid solution and ethanol
is effective in promoting a porous medium on the metal surface that improves the number of active
sites for the oxidation of copper ions and, consequently, promotes a more uniform growth of the
oxides.After selecting the best pre-treatment, the thermal process was evaluated through a 33
factorial experimental design using as parameters: the temperature (400-700 °C), the heating rate
up to the threshold temperature (5-15 ° C/min) and process duration (3-9 hours). The samples were
analyzed for the presence of nanowire structures and its diameters. Crystalline structures were
identified as oxide copper I and II (CuO and Cu2O) in addition to metallic copper in all tests
performed. The nanowires have diameters that vary between 60 and 120 nm. The analysis of
variance (ANOVA) for the factorial design tests 33 indicated, with a 95% reliability level, that the temperature and the heating rate had an influence on the concentration and the average diameter of the nanostructures obtained.