NANOCOMPÓSITOS BASEADOS EM QUANTUM DOTS DE CdS E CdS:Cu SUPORTADOS EM MERCAPTOPROPILSÍLICA:síntese, caracterização e aplicação em fotocatálise. / NANOCOMPOSITES BASED ON CdS AND CdS:Cu QUANTUM DOTS SUPPORTED ON MERCAPTOPROPYL-SILICA: synthesis, characterization and application in photocatalysis.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2011

RESUMO

Textile dyes and other commercial dyestuffs have become a focus of environmental remediation efforts in the last few years. Considerable attention has been expended recently on the photocatalytic oxidative degradation of colored contaminants in waste water over semiconductor surfaces. In this work, we evaluated the photocatalytic activities of nanocomposites based on cadmium sulfide (CdS) quantum dots anchored on (mercaptopropyl)silica (MPS) monitoring the photodegradation of methylene blue and rhodamine 6G aqueous solutions under sunlight irradiation. Herein, MPS was selected as the stabilizing agent to prepare the CdS and CdS doped with Cu2+ Qdots by the chemical reaction of cadmium acetate and thiourea in dimethylformamide Abstract|viii (DMF) by a rather simple one-step method. The quantum size effect has been monitored by UVvisible spectroscopy, which showed a blue shift of about 1648 nm relative to bulk CdS in the range 442-474 nm. Particle sizes calculated from Bruss model were found to be dependent on the MPS amount. These results evidenced that as-prepared CdS nanocrystals behave as Qdots. Additionally, XRD mensurements and HRTEM images indicated CdS cubic structure for the nanocrystals, which also exhibited an increment in the fluorescence intensity with decreasing particle size. UV absorption spectra for Cu-doped CdS are essentially similar to that of the undoped Qdots, but the luminescence properties are quite different from those of the undoped samples. Moreover, these materials could effectively degrade the organic dyes under sunlight irradiation by pseudo-first-order kinetics. This suggested that the CdS Qdots prepared in this work can be used as the potential photocatalyst to effectively treat the organic pollutants under sunlight irradiation.

ASSUNTO(S)

quantum dots sulfeto de cádmio rodamina 6g engenharia de materiais e metalurgica quantum dots fotocatálise heterogênea azul de metileno cadmium sulfide heterogeneous photocatalysis methylene blue rhodamine 6g

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