Síntese e aplicações de nanocristais semicondutores de ZnCdTe em matriz de grafeno

• Ano de defesa: 2018
• Autor(a) principal: Santana, Paula de Cássia Andrade
• Orientador(a): Sussuchi, Eliana Midori
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Química
• Palavras-chave em Português: Química; Química inorgância; Ponto quântico; Grafeno; Análise eletroquímica; Detecção eletroquímica; Carbendazim; Degradação sonocatalítica; Azul de metileno
• Palavras-chave em Inglês: Quantum dots; Graphene; Electrochemical detection; Sonocatalytic degradation; Methylene blue
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: http://ri.ufs.br/jspui/handle/riufs/7668

In the present study, a new nanocomposite based on ZnCdTe semiconductor nanocrystals synthesized in situ on reduced graphene oxide was obtained. The characterization of the heterostructure was done by transmission electronic microscopic and using spectroscopic emission and UV-Vis absorption techniques, where it was possible to observe the growth of nanocrystals in the rGO reduced graphene oxide matrix, as well as to estimate the value of the optical band gap. Cyclic voltammetry was used as a complementary characterization technique which was created to investigate the surface of the nanomaterial and calculate the band gap, obtaining approximate value to the optic. The study of the multifunctionality in applications of the obtained nanocomposite was carried out using the material as base of an electrochemical sensor and also, as a catalyst in the process of degradation of the methylene blue dye by exposure to the ultrasound waves, using the sonocatalysis procedure. To evaluate the electrochemical properties of the modified carbon paste electrodes with nanocomposite were prepared, with an effective area equal to 0.30 cm2. The modified electrode showed high sensitivity in the detection of the pesticide carbendazim. The parameters for the best conditions of analysis were established and a calibration curve was constructed with a behavior proportional to the concentration of the electroactive species in a linear range of 9.98.10-8 to 1.20.10-5 mol L-1, with limit of detection and quantification equal to 9.20.10-8 and 2.80.10-7 mol L-1, respectively. The method developed was applied in real samples of orange juice, which detected a concentration of 2.91.10-5 mol L-1 of the analyte, above that allowed by the legislation, indicating a possible contamination of the matrix. The sonocatalytic procedure demonstrated that the presence of the nanocomposite as a catalyst in the dye degradation process favored the dye degradation reaction speed in which it was possible to observe its color change during the time of exposure to the ultrasonic energy.