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Síntese de WO3 e de heteroestruturas WO3/TiO2 pelo método de oxidação por peróxido e avaliação do potencial como fotocatalisadores
(Universidade Federal de São Carlos, 2015-12-08) Castro, Isabela Alves de; Oliveira, Cauê Ribeiro de; https://lattes.cnpq.br/5321313558714462; https://lattes.cnpq.br/6065794585346231
The use of semiconductors for environmental applications and solar photoconversion has been widely explored recently. Due the intensive researches on renewable energy such as the photoelectrochemical H2 evolution from water splitting reaction, the design of new catalysts has been investigated. In this context, tungsten oxide – WO3 – is a promising catalyst for such application, however its conduction band is located at a more positive potential than the potential of water reduction, as a result WO3 does not have the ability to reduce H+ to H2. In the first part, this work deal with the synthesis of WO3 by the oxidant peroxide method, as a promising catalyst for this reaction. Tuning of the band-edge levels for the different synthesized catalysts was verified from Mott Schottky plot, and it represents the effective photoelectrocatalytic water splitting.In the second part, the study of heterostructuring TiO2 with WO3was investigated because of the possibility to mitigate the recombination of electron–hole pairs and therefore obtain more active systems for photocatalytic applications. The synthesis of WO3/TiO2 heterostructures was evaluated by hydrothermal method using three different routes: (I) precursors used as peroxo-complexes; (II) tungsten peroxo-complex and TiO2 pre-formed oxide; (III) pre-formed oxides as building blocks. The results showed by electrochemical characterization demonstrated how the electronic parameters (band edge positions, Fermi level energy and charge migration) affect the photocatalytic activity of heterostructures obtained by the distinct synthetic routes. The as-synthesized materials was investigated toward the photodegradation of organic dye (Rhodamine-B) under visible and UV illumination. The growth mechanism was observed to play a significant role in governing surface and interfacial properties, which has a direct influence on xvi materials photoactivity. The band edge positions for the materials was determined from Mott Schottky plot and the experimentally determined energy diagram is consistent with the formation of a type II heterostructure for WO3/TiO2 and it is well correlated to recent reports in literature. As a result, the photogenerated electrons and holes can be spatially distributed in two different crystalline phases in contact and the charge recombination is inhibited, which is efficient for photocatalytic reactions.Additionally, regarding the energy diagram obtained for the heterostrucutres, it is possible from the thermodynamic aspect the use of those structures as promising candidates for the photoelectrocatalytic water splitting, since the band positions are sufficiently large to overcome the character of this reaction.
Alunos dotados e talentosos : estarão eles em minha sala de aula?
(Universidade Federal de São Carlos, 2015-12-08) Oliveira, Roseli Figueiredo Correa de; Rangni, Rosemeire de Araújo; https://lattes.cnpq.br/6399149504309769; https://lattes.cnpq.br/5100198429357677
Inclusive education allows the presence in the mainstream classroom students with disabilities, disorders and giftedness and talent. For the gifted and talented students are subjects of the educational process, it is important that the teacher knows what's giftedness and talent to identify the students in the classroom and they can be assisted. With this research, it was intended as a general objective to verify if there is indication of gifted students in a 3rd year class and the 4th year of elementary school from two public schools, a total of four investigated classes, applying the tools Observação Direta em Sala de Aula, Lista De Verificação de Identificação de Indicadores de Altas Habilidades/Superdotação, Lista de Verificação de Identificação de Indicadores de Altas Habilidades/Superdotação-Área Artística, and Lista de Verificação de Identificação de Indicadores de Altas Habilidades/Superdotação-Área Corporal Cinestésica. The specific objectives were: To know the gifted and talented students indicated in schools with indexes appointed by (Index of development of basic education (IDEB), namely: a school with the lowest levels ( 3rd and 4th years ) and one with the highest levels ( 3rd and 4th years) at elementary school in a midsized city in the countryside of São Paulo, Brazil and to know the professional profile of the participanting teachers at the research, both in the academic aspect as in their teaching experience as well as theoretical knowledge on the subject of the giftedness and talent. The method was descriptive research. We used a questionnaire to characterize the participating teachers and knowledge on the subject. The results were: School A: (IDEB below) : With the Guia de Observação Direta em Sala de Aula was nominated four students (two of 3rd year and two of 4th year). The LIVIAHSD appointed a student of 3rd year. School B (IDEB above): the Guia de Observação Direta em Sala de Aula indicated nine students (four of 3rd year and five of 4th year). The LIVIAHSD indicated only two students in the 3rd year. The LIVIAHSD-AA and LIVIAHSD-ACC instruments did not indicate any student. The results still showed that: a) the instruments seemed effective to point gifted students; b) LIVIAHSD, LIVIAHSD-AA and LIVIAHSD-ACC didn’t have the same efficiency of the Guia de Observação Direta em Sala de Aula, requiring their completion for comparison and analysis; c) The IDEB schools up and down revealed that there were gifted students, independently the indexes of IDEB, and d) The most of teachers surveyed made explicit about the understanding of the giftedness and talent subject.