Gleice
@uft.edu.br
Química Ambiental
Universidade Federal do Tocantins
Scopus Publications
Scopus Publications
M.A.S. Alencar, M.K.D. Rambo, G.L.G.T. Botelho, P.M.M. Barros, R.L. Sergio, M.S. Borges, and D. Bertuol
Elsevier BV
Mayre Manny Porto Barros, Karla Jackeline Costa Almeida, Marcus Vinicius Sousa Conceição, Douglas Henrique Pereira, and Gleice Botelho
Elsevier BV
M. M. P. Barros, K. C. Almeida, S. A. Silva, and G. Botelho
FapUNIFESP (SciELO)
Gleice Lorena Gonçalves Tavares Botelho, Camila Cristina De Foggi, Carlos Eduardo Vergani, Wyllamanney Silva Pereira, Ricardo Kaminishi Dos Santos Júnior, and Elson Longo
Instituto de Quimica - Univ. Federal do Mato Grosso do Sul
Ricardo K. Santos, Tiago A. Martins, Gabriela N. Silva, Marcus V. S. Conceição, Içamira C. Nogueira, Elson Longo, and Gleice Botelho
American Chemical Society (ACS)
Black NiO powders were prepared by a hydrothermal method. Moreover, the visible light-driven Ag3PO4/NiO photocatalyst composites were successfully synthesized by in situ precipitation method. These samples were structurally characterized by X-ray diffraction and Rietveld refinement. The strong interaction between the phases and the defects in the samples was affected by the formation of the composites, as identified by Fourier transform infrared spectroscopy and Raman spectroscopy. UV–vis diffuse reflectance spectroscopy exhibited enhanced light absorption for all Ag3PO4/NiO composites, suggesting the effective interaction between the phases. Moreover, field-emission scanning electron microscopy images revealed the presence of NiO microflowers composed of nanoflakes in contact with Ag3PO4 microparticles. The composite with 5% NiO presented enhanced photocatalytic efficiency in comparison with pure Ag3PO4, degrading 96% of rhodamine B (RhB) dye in just 15 min under visible light; however, the recycling experiments confirmed that the composite with 75% NiO showed superior stability. The recombination of the electron–hole pairs was considered for the measurement of the photoluminescence of the samples. These measurements were performed to evaluate the possible causes for the difference in the photocatalytic responses of the composites. From these experimental results, possible photocatalytic mechanisms for RhB degradation over Ag3PO4/NiO composites under visible-light irradiation were proposed.
Wyllamanney da S. Pereira, Júlio C. Sczancoski, Yormary N.C. Calderon, Valmor R. Mastelaro, Gleice Botelho, Thales R. Machado, Edson R. Leite, and Elson Longo
Elsevier BV
Abstract Materials presenting high photocatalytic performance and interesting photoluminescence emissions are promising candidates for photodegradation of organic pollutants discharged into natural waters as well as for development of new electro-optical devices, respectively. In this study, Ag3-2xCuxPO4 (x = 0.00, 0.01, 0.02, 0.04 and 0.08) powders were synthesized by the precipitation method. The long- and short-range structural ordering was affected when the copper (Cu) content was increased in the lattice, as identified by X-ray diffraction patterns, Fourier transform infrared spectroscopy and Raman spectroscopy, respectively. The field emission scanning electron microscope and transmission electron microscope revealed a particle system composed of irregular spherical-like microcrystals. The presence of Cu as well as its real amount in the samples were confirmed by means of X-ray photoelectron spectroscopy and inductively coupled plasma-atomic emission spectrometry, respectively. On increasing Cu level, a slight variation was noted on the photocatalytic activity of Ag3-2xCuxPO4 powders for degradation of rhodamine B under visible light irradiation. A photodegradation mechanism was proposed in details. The photoluminescence emissions were explained by electronic transitions involving intermediary energy levels in the band gap. The origin these energy levels was related to defects caused by the substitution of Ag by Cu in the crystalline structure.
Paula F. S. Pereira, Clayane C. Santos, Amanda F. Gouveia, Mateus M. Ferrer, Ivo M. Pinatti, Gleice Botelho, Julio R. Sambrano, Ieda L. V. Rosa, Juan Andrés, and Elson Longo
American Chemical Society (ACS)
A theoretical study was elaborated to support the experimental results of the Zn-doped α-Ag2WO4. Theses α-Ag2-2xZnxWO4 (0 ≤ x ≤ 0.25) solid solutions were obtained by coprecipitation method. X-ray diffraction data indicated that all α-Ag2-2xZnxWO4 (0 ≤ x ≤ 0.25) microcrystals presented an orthorhombic structure. The experimental values of the micro-Raman frequencies were in reasonable agreement with both previously reported and calculated results. Microscopy images showed that the replacement of Ag+ by Zn2+ promoted a reduction in the average crystal size and modifications in the morphology, from rod-like with hexagonal shape to roll-like with a curved surface. A theoretical methodology based on the surfaces calculations and Wulff constructions was applied to study the particle shapes transformations and the surface energy variations in α-Ag2-2xZnxWO4 (0 ≤ x ≤ 0.25) system. The decrease in the band gap value (from 3.18 to 3.08 eV) and the red shift in photoluminescence with the Zn2+ addition were associated with intermediary energy levels between the valence and conduction bands. First-principles calculations with density functional theory associated with B3LYP hybrid functional were conducted. The calculated band structures revealed an indirect band gap for the α-Ag2-2xZnxWO4 models. The electronic properties of α-Ag2WO4 and α-Ag2-2xZnxWO4 microcrystals were linked to distortion effects and oxygen vacancies (VOx) present in the clusters, respectively. Finally, photoluminescence properties of α-Ag2WO4 and α-Ag2-2xZnxWO4 microcrystals were explained by means of distortional effects and oxygen vacancies (VOx) in [AgOy] (y = 2, 4, 6, and 7) and [WO6] clusters, respectively, causing a red shift. Calculations revealed that the substitution for Ag+ with Zn2+ occurred randomly in the α-Ag2WO4 lattice, and it was more favorable on the Ag4 site, where the local coordination of Ag+ cations was four.
F.A. La Porta, A.E. Nogueira, Lourdes Gracia, W.S. Pereira, G. Botelho, T.A. Mulinari, Juan Andrés, and E. Longo
Elsevier BV
Abstract From the viewpoints of materials chemistry and physical chemistry, crystal structure directly determines the electronic structure and furthermore their optical and photocatalytic properties. Zinc sulfide (ZnS) nanoparticles (NPs) with tunable photoluminescence (PL) emission and high photocatalytic activity have been obtained by means of a microwave-assisted solvothermal (MAS) method using different precursors (i.e., zinc nitrate (ZN), zinc chloride (ZC), or zinc acetate (ZA)). The morphologies, optical properties, and electronic structures of the as-synthesized ZnS NPs were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) isotherms for N2 adsorption/desorption processes, diffuse reflectance spectroscopy (DRS), PL measurements and theoretical calculations. Density functional theory calculations were used to determine the geometries and electronic properties of bulk wurtzite (WZ) ZnS NPs and their (0001), (101 0), (112 0), (101 1), and (101 2) surfaces. The dependence of the PL emission behavior of ZnS NPs on the precursor was elucidated by examining the energy band structure and density of states. The method for degradation of Rhodamine B (RhB) was used as a probe reaction to investigate the photocatalytic activity of the as-Synthesised ZnS NPs under UV light irradiation. The PL behavior as well as photocatalytic activities of ZnS NPs were attributed to specific features of the structural and electronic structures. Increased photocatalytic degradation was observed for samples synthesized using different precursors in the following order: ZA
G. Botelho, I.C. Nogueira, E. Moraes, and E. Longo
Elsevier BV
Abstract Calcium molybdate (CaMoO 4 ) nanoparticles were synthesized by using a rapid assisted-microwave solvothermal method. X-ray diffraction measurements, Fourier transform Raman and Fourier transform infrared spectroscopies, revealed that the samples all have a scheelite-type tetragonal structure. In addition, the data obtained from the Rietveld refinements revealed distortions of the [Ca O] and [Mo O] bonds that led, in turn, to distortions of the [CaO 8 ] and [MoO 4 ] clusters. The presence of irregular spherical-like CaMoO 4 nanoparticles and the corresponding crystallographic arrangement were confirmed and determined via transmission electron microscopy and high resolution transmission electron microscopy, respectively. First-principles quantum mechanical calculations based on the density functional theory at the B3LYP level were employed in order to understand the band structure and density of states of CaMoO 4 in the excited singlet and triplet states. Furthermore, the optical properties were investigated by performing ultraviolet–visible spectroscopy and photoluminescence (PL) measurements. Maximum PL emission of CaMoO 4 powders was detected in the green-region wavelength of the electromagnetic spectrum; this emission was attributed to the distorted [MoO 4 ] clusters.
Gleice Botelho, Juan Andres, Lourdes Gracia, Leandro S. Matos, and Elson Longo
Wiley
The structural, morphological, and optical properties of Ag3 PO4 microcrystals were systematically characterized by using a combination of theoretical calculations and experimental techniques. These microcrystals were synthesized by the microwave-assisted hydrothermal (MAH) method. XRD, Rietveld refinements, and FTIR spectroscopy were employed to carry out a structural analysis; the morphologies of the microcrystals were examined by FEG-SEM. First-principles computational studies were used to calculate the geometries of bulk Ag3 PO4 and its (010), (100), (001), (110), (101), (011), and (111) surfaces. A continuous decrease in the energy of the (100) surface led to a good agreement between the experimental and theoretical morphologies. Optical properties were investigated by UV/Vis spectroscopy and photoluminescence (PL) measurements, which revealed a maximum PL emission at λ=444 nm. The MAH-synthesized sample exhibited good activity for the photocatalytic degradation of methyl orange dye under visible irradiation. The photocatalytic activity and PL behavior were correlated with the observed morphology.
Wyllamanney da Silva Pereira, Mateus Meneghetti Ferrer, Gleice Botelho, Lourdes Gracia, Içamira Costa Nogueira, Ivo Mateus Pinatti, Ieda Lúcia Viana Rosa, Felipe de Almeida La Porta, Juan Andrés, and Elson Longo
Royal Society of Chemistry (RSC)
In this work, we investigated the effects of chemical substitution of α-Ag2−2xNixWO4(0 ≤x≤ 0.08) solid solutions prepared by a facile microwave-assisted hydrothermal method.
G. Botelho, J. C. Sczancoski, J. Andres, L. Gracia, and E. Longo
American Chemical Society (ACS)
Theoretical and experimental studies were performed on the structure, optical properties, and growth of silver nanostructures in silver phosphate (Ag3PO4). This material was synthesized by the coprecipitation method and processed in a microwave-assisted hydrothermal system at 150 °C for different times. The structural behavior was analyzed by means of X-ray diffraction, Rietveld refinement, and Raman spectroscopy. Field emission gun scanning electron microscopy as well as transmission electron microscopy revealed the presence of irregular spherical-like Ag3PO4 microparticles; metallic silver nanostructures were found on their surfaces. The growth processes of Ag nanostructures when irradiated with an electron beam were explained by theoretical calculations. First-principles calculations, within a quantum theory of atoms in molecules framework, have been carried out to provide deeper insight and understanding of the observed nucleation and early evolution of Ag nanoparticles on Ag3PO4 crystals, driven by a...