Growth mechanism and photocatalytic properties of SrWO4 microcrystals synthesized by injection of ions into a hot aqueous solution

Advanced Powder Technology Volume: 24 Issue: 1 Pages: 344-353 Published: 2013

Fig. 4. (a and b) Low magnification FE-SEM images of rice-like SrWO4 microcrystals, (c) high magnification FE-SEM images of star-like SrWO4 microcrystals, (d) high magnification FE-SEM images of flower-like SrWO4 microcrystals and (e) high magnification FE-SEM images of urchin-like SrWO4 microcrystals.

Writers: L.S. Cavalcante, J.C. Sczancoski, N.C. Batista, E. Longo, J.A. Varela, M.O. Orlandi

Keywords: SrWO4; Rhodamine; Rietveld refinement; Hot-injection; Photocatalysis

Abstract: This paper reports our initial research to obtain SrWO4 microcrystals by the injection of ions into a hot aqueous solution and their photocatalytic (PC) properties. These microcrystals were structurally characterized by X-ray diffraction (XRD), Rietveld refinements and Fourier transform (FT)-Raman spectroscopy. The shape and average size of these SrWO4 microcrystals were observed by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). In addition, we have investigated the PC activity of microcrystals for the degradation of rhodamine B (RhB) and rhodamine 6G (Rh6G) dyes. XRD patterns, Rietveld refinement data and FT-Raman spectroscopy confirmed that SrWO4 microcrystals have a scheelite-type tetragonal structure without deleterious phases. FT-Raman spectra exhibited 12 Raman-active modes in a range from 50 to 1000 cm−1. FE-SEM and TEM images suggested that the SrWO4 microcrystals (rice-like – 95%; star-, flower-, and urchin-like – 5%) were formed by means of primary/secondary nucleation events and self-assembly processes. Based on these FE-SEM/TEM images, a crystal growth mechanism was proposed and discussed in details in this work. Finally, a good PC activity was first discovered of the SrWO4 microcrystals for the degradation of RhB after 80 min and Rh6G after 50 min dyes under ultraviolet-light, respectively.

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DOI: 10.1016/j.apt.2012.08.007

Robson Lima
Sobre Robson Lima 38 Artigos
Atua no Centro de Desenvolvimento de Materiais Funcionais.