Notícias

Banca de DEFESA: ANNA THAISE BANDEIRA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE: ANNA THAISE BANDEIRA SILVA
DATA: 12/06/2015
HORA: 14:30
LOCAL: Auditório da Química
TÍTULO:

Nanocubos do análogo de azul da Prússia de cobalto modificados por nanopartículas ferromagnéticas


PALAVRAS-CHAVES:

análogo de azul da Prússia de cobalto, nanopartículas ferromagnéticas, supramolecular.


PÁGINAS: 70
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Inorgânica
ESPECIALIDADE: Campos de Coordenação
RESUMO:

ABSTRACT: Based on cobalt Prussian blue analogue complex (Co3[Co(CN)6]2) and ferromagnetic nanoparticles (Fe3O4 NPs) a novel Co3[Co(CN)6]2/Fe3O4 nanomaterial was developed. The preparation of the functional material involved the self-assembly of Fe3O4 NPs onto a Co3[Co(CN)6]2 surface by co-precipitation method. The electronic spectrum of colloidal dispersion of Co3[Co(CN)6]2/Fe3O4  did not exhibit the shoulder characteristic of the analogue complex. Indeed, the increase of the baseline was occasioned by nanoparticles formation causing light scattering. Evidence of the formation of the colloidal dispersion was observed by Tyndall effect. According to transmission electronic microscopy results, Co3[Co(CN)6]2/Fe3O4 nanomaterial exhibited a polidispersed organizational structure composed of Co3[Co(CN)6]2 nanocubes with a mean edge length of 115 nm decorated by spherical ferromagnetic nanoparticles with size lower than 20 nm. The intimate contact at supramolecular level among nanocubes with aggregates formation was avoided by Fe3O4 NPs. The FTIR spectrum of Co3[Co(CN)6]2/Fe3O4 system presented main bands (Fe-O, CN and Co-CN stretchings) that were also observed in the FTIR spectra of the isolated materials, Fe3O4 and Co3[Co(CN)6]2. The crystalline and thermal properties of the hybrid material were studied by X-ray diffraction and thermogravimetric analysis. The cyclic voltammogram of the hybrid material in a 0.1 mol L-1 NaCl supporting electrolyte exhibited a quasi-reversible redox process, attributed to Co2+/Co3+ conversion, with an E1/2 value of 0.46 V (vs SCE), with higher reversibility observed for the system in the presence of Fe3O4 NPs. Moreover, it was observed an increase of the faradaic current for voltammogram of Co3[Co(CN)6]2/Fe3O4 when compared to the isolated Co3[Co(CN)6]2. The standard rate constants for Co3[Co(CN)6]2 and Co3[Co(CN)6]2/Fe3O4 were determined to be 0.05 and 0.07 s−1, respectively, which suggests that the interaction between the nanocubes and nanoparticles at the supramolecular level improves electron transfer. We expect that the properties observed for the hybrid material make it a potential candidate for (bio)sensors development.


MEMBROS DA BANCA:
Presidente - 1508806 - WELTER CANTANHEDE DA SILVA
Interno - 1714171 - JANILDO LOPES MAGALHAES
Externo à Instituição - ALDO JOSÉ GORGATTI ZARBIN - UFPR
Notícia cadastrada em: 27/05/2015 15:52
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