Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a fast and facile sonochemical method

Article abstract of DOI:10.1016/j.jallcom.2019.153617

In this work, Ag⁺ and Zn²⁺ co-doped CaWO₄ nanoparticles were obtained by fast and facile sonochemical method. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), visible ultraviolet spectroscopy (UV–Vis) and photoluminescence property. The photocatalytic activity was studied against methylene blue (MB) dye under sunlight and CaWO₄ powders were tested in 3 reuse cycles. The diffractograms indicate the non-formation of secondary phases and the Rietveld refinement estimated the crystallite sizes, being 27.38, 19.89, 18.70 and 16.39 nm for the pure, Ag, Zn and Ag:Zn samples, respectively. SEM and TEM images showed that the particles are agglomerated and have a mean diameter ranging from 16.76 (Ag:Zn) to 71.76 nm (pure). Defects generated by doping shift the gap band to higher energies and act to prevent electron/hole (e^?/h⁺) pair recombination, reducing photoluminescence and favoring CaWO₄ photocatalysis. Scavenger methodology indicated that h⁺ is the main mechanism acting in photocatalysis, and the reuse tests indicated that the silver-doped sample, even with the better initial response, loses efficiency over the course of the cycle, while the co-doped sample maintains efficiency, and is therefore indicated for reuse photocatalysis applications in methylene blue dye degradation.

Full text of DOI:10.1016/j.jallcom.2019.153617

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Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a
fast and facile sonochemical method
N.F. Andrade Neto, B.P. Dias, R.L. Tranquilin, E. Longo, M. Li, M.R.D. Bomio, F.V.
Motta
PII:
S0925-8388(19)34863-7
DOI:
https://doi.org/10.1016/j.jallcom.2019.153617
JALCOM 153617
Reference:
To appear in: Journal of Alloys and Compounds
Received Date: 4 October 2019
Revised Date: 16 December 2019
Accepted Date: 30 December 2019
Please cite this article as: N.F.A. Neto, B.P. Dias, R.L. Tranquilin, E. Longo, M. Li, M.R.D. Bomio, F.V.
Motta, Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a fast and
facile sonochemical method, Journal of Alloys and Compounds (2020), doi: https://doi.org/10.1016/
j.jallcom.2019.153617.
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CRediT author statement
•
N. F. Andrade Neto: Conceptualization, Methodology, Software, Validation,
Investigation, Data Curation, Writing - Original Draft, Visualization,
Supervision, Project administration.
•
•
•
•
•
B. P. Dias: Methodology, Validation, Investigation, Visualization,
R. L. Tranquilin: Resources, Data Curation,
E. Longo: Resources, Data Curation,
M. Li: Resources, Data Curation,
M. R. D. Bomio: Conceptualization, Methodology, Validation, Investigation,
Resources, Writing - Original Draft, Visualization, Supervision, Project
administration, Funding acquisition.
•
F. V. Motta: Conceptualization, Methodology, Validation, Investigation,
Resources, Writing - Original Draft, Visualization, Supervision, Project
administration, Funding acquisition.

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Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by
a fast and facile sonochemical method
N.F. Andrade Neto1*, B.P. Dias1, R.L. Tranquilin2, E. Longo2, M. Li3, M.R.D. Bomio1,
F.V. Motta1.
1LSQM – Laboratory of Chemical Synthesis of Materials – Department of Materials
Engineering, Federal University of Rio Grande do Norte – UFRN, P.O. Box 1524, Natal
RN, Brazil.
2CDMF-UFSCar, Universidade Federal de São Carlos, P.O. Box 676, São Carlos, SP
13565 905, Brazil.
3IFSC, USP, Av. Trabalhador São Carlense, 400, CEP 13566-590 São Carlos, SP,
Brazil
*Corresponding author. Tel/fax: +55-84-3342-2406

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E-mail: netoandrade@ufrn.edu.br (N. F. Andrade Neto)
Abstract
In this work, Ag+ and Zn2+ co-doped CaWO4 nanoparticles were obtained by fast and
facile sonochemical method. The nanoparticles were characterized by X-ray diffraction
(XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy,
scanning electron microscopy (SEM), transmission electron microscopy (TEM), visible
ultraviolet spectroscopy (UV-Vis) and photoluminescence property. The photocatalytic
activity was studied against methylene blue (MB) dye under sunlight and CaWO4
powders were tested in 3 reuse cycles. The diffractograms indicate the non-formation of
secondary phases and the Rietveld refinement estimated the crystallite sizes, being
27.38, 19.89, 18.70 and 16.39 nm for the pure, Ag, Zn and Ag:Zn samples, respectively.
SEM and TEM images showed that the particles are agglomerated and have a mean
diameter ranging from 16.76 (Ag:Zn) to 71.76 nm (pure). Defects generated by doping
shift the gap band to higher energies and act to prevent electron/hole (e-/h+) pair
recombination, reducing photoluminescence and favoring CaWO4 photocatalysis.
Scavenger methodology indicated that h+ is the main mechanism acting in
photocatalysis, and the reuse tests indicated that the silver-doped sample, even with the
better initial response, loses efficiency over the course of the cycle, while the co-doped
sample maintains efficiency, and is therefore indicated for reuse photocatalysis
applications in methylene blue dye degradation.
Keywords: Sonochemical method; Ag and Zn co-doped CaWO4; photoluminescence;
photocatalysis.
1. Introduction