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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Electronic structure, optical and sonophotocatalytic properties of spindle-like CaWO4 microcrystals synthesized by the sonochemical method

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Author(s):
de Sousa, P. B. [1] ; Gouveia, A. F. [2] ; Sczancoski, J. C. [3] ; Nogueira, I. C. [4] ; Longo, E. [3] ; San-Miguel, M. A. [2] ; Cavalcante, L. S. [1, 5]
Total Authors: 7
Affiliation:
[1] Univ Fed Piaui, Campus Minist Petronio Portella, BR-64049550 Ininga, Teresina Pi - Brazil
[2] Univ Estadual Campinas, Inst Chem, BR-13083970 Campinas, SP - Brazil
[3] DEMA DQ Univ Fed Sao Carlos, POB 676, BR-13565905 Sao Carlos, SP - Brazil
[4] Univ Fed Amazonas, Av Rodrigo Otavio Japiim, POB 670, BR-69077000 Manaus, Amazonas - Brazil
[5] Univ Estadual Piaui, Rua Joao Cabral 2231, POB 381, BR-64002150 Teresina Pi - Brazil
Total Affiliations: 5
Document type: Journal article
Source: Journal of Alloys and Compounds; v. 855, n. 1 FEB 25 2021.
Web of Science Citations: 0
Abstract

In this letter, the electronic structure, optical, and sonophotocatalytic properties of calcium tungstate (CaWO4) microcrystals synthesized by the sonochemical method are reported. Structural and morphological characterization techniques revealed that CaWO4 has a tetragonal structure and composed of several spindle-like microcrystals. The ultraviolet-visible spectroscopy showed an optical band gap energy E-gap(exp) of 4.69 eV. The theoretical calculations were performed to describe the electronic band structure, the density of states, and Infrared/Raman vibrational modes. The theoretical models were based on optimized and defect-based structures. The theoretical optical band gap energy (E-gap) confirmed the existence of direct electronic transitions (Gamma <-> Gamma points in Brillouin zone). The optimized structure exhibited an E-gap(theo) value of 5.70 eV due to the participation of energy levels arising from O and Ca atoms in the valence band as well as W and O atoms in the conduction band. A decrease from 5.70 to 4.29 eV was observed for the defect-based structure. The sonophotocatalytic properties of CaWO4 microcrystals were investigated for the first time with respect to degradation of Rhodamine B dye and they revealed a degradation capacity of approximately 96% after 200 min. Finally, our electron density maps indicate that the presence of structural defects induces a polarization phenomenon and inhomogeneous distribution of electron charge between the {[}CaO8]-{[}WO4] clusters. (C) 2020 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 19/01732-1 - Photocatalytic activity of multifunctional semiconductors: influence of morphology and electron injection
Grantee:Amanda Fernandes Gouveia
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
Grantee:Elson Longo da Silva
Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC
FAPESP's process: 16/23891-6 - Computer modeling of condensed matter
Grantee:Alex Antonelli
Support type: Research Projects - Thematic Grants