ZnWO4 nanocrystals prepared by thermal plasma processing

Author(s)

de Araujo, L. N. M. ; Sousa, B. S. ; de Araujo, A. G. F. ; Moncao, R. M. ; Feitor, M. C. ; Sczancoski, J. C. ; Almeida, M. A. P. ; Santos, F. E. P. ; de Sousa, R. R. M. ; Cavalcante, L. S.

• Document type: Journal article
• Source: Journal of Materials Science; v. 58, n. 16, p. 28-pg., 2023-04-13.

Abstract

In this paper, we propose a new way of making pure zinc tungstate (ZnWO4) nanocrystals through thermal plasma processing. Initially, we prepared amorphous powders by the coprecipitation method at room temperature and then, these powders were processed at different temperatures between 400 and 600 degrees C for 1 h by the thermal plasma technique. Structural analyses with characterizations by X-raydiffraction, Rietveld refinement data, micro-Raman, and Fourier transform-infrared spectroscopies indicate a transition from the amorphous phase (coprecipitated) to intermediate (W18O49 and ZnO phases) and desired ZnWO4 phase between 400 and 550 degrees C for 1 h. These characterizations confirmed the best effectof thermalplasma at 600 degrees C for 1 h to obtain single-phase ZnWO4 pristine with a wolframite-type monoclinic structure and typical vibrational modes. The ultravioleta-visible diffuse reflectance spectroscopy revealed a decrease in optical band energy values from 3.97 to 3.20 eV. Field emission scanning electron microscopy showed clear images of a considerable morphological modification of small spherical and irregular particles referring to the W18O49 andZnOphases to a growth more homogeneous of rod-like ZnWO4 nanocrystals related to pristine phase with size from 132 to 155 nm. The sonocatalytic, photocatalytic, and sonophotocatalytic (SPC) properties for degradation of Rhodamine 6G (Rh6G) were investigated. The better SPC degradation rate at Rh6G dye in 80 min was performed with ZnWO4 nanocrystals processed at 600 degrees C. Finally, the radical scavengers assays indicated that hydroxyl (center dot OH) and superoxide (O-2(-)) radicals are themain ones responsible for the chemical reactions to Rh6G dye degradation. [GRAPHICS] . (AU)

• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 12/14004-5 - Investigation of the photoluminescence and photocatalytic properties of pure and Mn, Cu, and Zn-doped BaWO4 and BaMoO4 powders
• Grantee: Júlio César Sczancoski
• Support Opportunities: Scholarships in Brazil - Post-Doctoral