Camila Cholant - Academia.edu (original) (raw)
Papers by Camila Cholant
Electrochimica Acta, May 1, 2019
Since 1980´s natural polymers are studied as sources for solid polymer electrolytes (SPEs) in opt... more Since 1980´s natural polymers are studied as sources for solid polymer electrolytes (SPEs) in opto-electronic equipment because of their abundance in the environment, inexpensiveness, and biological degradation characteristics. Xanthan gum is a naturally occurring polysaccharide found in the microbial world, and its main advantage is to produce transparent solutions with elevated viscosity and stability including wide range of temperature. Therefore, the present paper presents the FTIR and impedance study of xanthan gum as a host matrix for the ionically conducting membranes. Different contents of proton conducting species were incorporated into the polymer host and the membranes were realized by the method of solution casting. The FTIR results indicated that the electrolytes were formed by the polymeric network. The frequency independent conductivity response pointed the best dc conductivity values of 7.2610-5 to 3.9210-4 S.cm-1 , in the temperature range from 20 to 80 o C, for the sample with 2.00 g of acetic acid. The occurrence of the electrode polarization was interpreted by the combination of the complex dielectric permittivity (*), loss tangent (tan ), conductivity (), and complex electric modulus (M*).
Materials Research-ibero-american Journal of Materials, 2019
Concrete is the most used material in the construction industry worldwide. Built concrete infrast... more Concrete is the most used material in the construction industry worldwide. Built concrete infrastructure is exposed to specific environments conditions during the asset's life, which impose chemical and physical actions that may lead to premature deterioration. Poor concrete durability and corrosion of reinforcement bars are the primary cause of structural deterioration and reduced service life. Most concrete deterioration mechanisms are driven by transport properties, in particular, the chloride diffusion coefficient. In this paper, the effect of curing in the chloride diffusion coefficient of conventional concrete is investigated through Electrochemical Impedance Spectroscopy (EIS). Reinforced concrete samples cured for 3, 7 and 28 days were exposed to accelerated chloride testing for 300 days (40 wet-dry cycles). Results indicate that the chloride diffusion coefficient reduces significantly with curing time, evidencing that prolonged curing may decrease the likelihood of corrosion in reinforced concrete structure when combined with appropriate design and construction processes.
Journal of Electronic Materials, Jan 3, 2021
This paper presents a study of physical and electrochemical properties relevant to the lithium io... more This paper presents a study of physical and electrochemical properties relevant to the lithium ion diffusion process governing WO3 thin films electrochromic phenomenon. The films were prepared from a solution obtained by the sol–gel process and deposited via dip-coating. They were characterized by chronocoulometry, chronoamperometry and in and ex situ ultraviolet–visible spectroscopy during coloring/bleaching of the films. To analyze the experimental data, a mathematical model was applied considering a reaction kinetics controlled by the diffusion of ion pairs. The effects of the intercalation of Li+, Na+ and K+ ions was compared. Theoretical and experimental results for the current, charge density and absorbance profiles in function of time are included in this paper. The highest values obtained were η=29.98C/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}eta=29.98,textC/cm2\eta = 29.98\,{\text{C/cm}}^{2}eta=29.98,textC/cm2\end{document} for electrochromic efficiency, ΔT = 61.6% for optical modulation, Qi=81.78mC/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}Qi=81.78,textmC/cm2Q_{i} = 81.78\,{\text{mC/cm}}^{2}Qi=81.78,textmC/cm2\end{document} for charge density, and reversibility of coloring/bleaching in the range of 75–90%. X-Ray diffractometry measurements confirmed the amorphous structure of the films. Fourier transform infrared spectroscopy was employed to analyze the functional groups present in the films structure, while their topology was studied via atomic force microscopy. The collected results confirmed a relationship between the electrochromic and electrochemical reactions, definitively associating color change with cations injection and the reduction of W6+ to W5+.
Optical Materials, Jun 1, 2022
Materials Chemistry and Physics
Journal of The Electrochemical Society
Herein, we have developed a new biopolymer gel electrolyte based on xanthan, a material widely us... more Herein, we have developed a new biopolymer gel electrolyte based on xanthan, a material widely used in the food and pharmaceutical industry. The incorporation of the ionic liquids 1-butyl-2,3-dimethylimidazolium iodide (BMMI.I) and 1-ethyl-2,3-dimethylimidazolium iodide (EMMI.I) has significantly enhanced ionic conductivity by 136% and 181%, respectively. These ionic liquids possess a substantial permanent dipole moment, which can induce the alignment of other dipoles around them, through conformational changes. The interplay between the ionic liquid and the segmental motion of the polymer was investigated through temperature-dependent conductivity measurements using the Vogel-Tamman-Fulcher equation. Analysis of the complex dielectric (ε′and ε″) constants revealed the polarization effect of ionic species at the electrode/electrolyte interface. Additionally, the analysis of the complex electric modulus (M′and M″) and the loss tangent (tang δ) show that the incorporation of EMMI.I re...
Biomass Conversion and Biorefinery
Materials Research Bulletin, 2021
Abstract Thin films of cerium dioxide (CeO2) and cerium dioxide doped with vanadium pentoxide (Ce... more Abstract Thin films of cerium dioxide (CeO2) and cerium dioxide doped with vanadium pentoxide (CeO2:V2O5) were prepared through sol-gel route and spin coating deposition, for use as smart materials. This work evaluated films that underwent a weathering process in an accelerated weathering test chamber and the changes in their properties. The influence of the temperature was also studied electrochemically. Regarding the weathering process, there were variations in the charge insertion capacity during the investigated period. However, at the end of the 900 simulated days, the CeO2:V2O5 presented interesting values. For the EIS analyses, the curve (Nyquist plot) remained about 45° inclination, suggesting a diffusional process. The morphological and structural analyses demonstrated that by doping the film, occurs a reduction on the degradation, although the structure showed no changes. For different temperatures, the film becomes more resistive as the temperature increases. The chronocoulometry showed that the charge insertion capacity increases with temperature.
Ionics, 2022
The present study investigates the preparation and properties of solid polymer electrolytes based... more The present study investigates the preparation and properties of solid polymer electrolytes based on poly(vinyl alcohol) (PVA) and gum Arabic (GA). The Fourier transform infrared spectroscopy was used to demonstrate the interaction between PVA/GA and LiClO4 via -COO- and -OH functional groups and the electrochemical impedance spectroscopy to study the dielectric properties in a frequency range between 106 and 101 Hz and temperatures from 25 to 80 °C. This last revealed that the conductivity increases with the temperature, indicating an ion conduction and segmental movements of the polymer. Moreover, changes in the peak positions of the loss tangent at high frequencies indicated a decrease in relaxation time and an increase in ionic dynamics as a function of temperature. From the DC polarization, ion and electron transference numbers of PVA/GA24 were 0.997 and 0.003, respectively. Finally, long cyclic voltammetry (CV) cycle and thermal stability measures support that PVA/GA polymer electrolytes possess suitable characteristics for solid-state lithium-ion batteries or electrochemical double-layer capacitors.
This work aims to analyze the thermoenergetic and luminous performance of a building with office ... more This work aims to analyze the thermoenergetic and luminous performance of a building with office characteristic activities with electrochromic glasses through comparative study, considering common glasses of 3mm and 6mm. For the computational simulation were used the EnergyPlus software. Simulations were performed with the Clear common glass Clear of 3 mm and 6 mm and the electrochromic glass Sage Glass 9 mm with the purpose of analyzing the lighting, the energy consumption, and the level of thermal comfort coming from the artificial climatization and the natural ventilation, respectively. The simulations were performed in two bioclimatic zones, in bioclimatic zone 2 (ZB 2) and in bioclimatic zone 8 (ZB 8), where it was used the climate files from the city of Camaquã and the city of Manaus, respectively. With the results obtained it was possible to observe that the building with electrochromic glasses presented the best level of thermal comfort in the hours occupied, and that the en...
Journal of Electronic Materials, 2021
This paper presents a study of physical and electrochemical properties relevant to the lithium io... more This paper presents a study of physical and electrochemical properties relevant to the lithium ion diffusion process governing WO3 thin films electrochromic phenomenon. The films were prepared from a solution obtained by the sol–gel process and deposited via dip-coating. They were characterized by chronocoulometry, chronoamperometry and in and ex situ ultraviolet–visible spectroscopy during coloring/bleaching of the films. To analyze the experimental data, a mathematical model was applied considering a reaction kinetics controlled by the diffusion of ion pairs. The effects of the intercalation of Li+, Na+ and K+ ions was compared. Theoretical and experimental results for the current, charge density and absorbance profiles in function of time are included in this paper. The highest values obtained were η=29.98C/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}eta=29.98,textC/cm2\eta = 29.98\,{\text{C/cm}}^{2}eta=29.98,textC/cm2\end{document} for electrochromic efficiency, ΔT = 61.6% for optical modulation, Qi=81.78mC/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}Qi=81.78,textmC/cm2Q_{i} = 81.78\,{\text{mC/cm}}^{2}Qi=81.78,textmC/cm2\end{document} for charge density, and reversibility of coloring/bleaching in the range of 75–90%. X-Ray diffractometry measurements confirmed the amorphous structure of the films. Fourier transform infrared spectroscopy was employed to analyze the functional groups present in the films structure, while their topology was studied via atomic force microscopy. The collected results confirmed a relationship between the electrochromic and electrochemical reactions, definitively associating color change with cations injection and the reduction of W6+ to W5+.
Matéria (Rio de Janeiro), 2020
RESUMO Este trabalho tem como objetivo analisar o desempenho termoenergético e luminoso de uma ed... more RESUMO Este trabalho tem como objetivo analisar o desempenho termoenergético e luminoso de uma edificação com atividades características de escritórios com vidros eletrocrômicos através de estudo comparativo, considerando vidros comuns de 3mm e 6mm. Para a simulação computacional foi utilizado o programa EnergyPlus . Foram realizadas simulações com o vidro comum Clear 3mm e de 6mm e o vidro eletrocrômico Sage Glass 9mm com a finalidade de analisar a iluminação, o consumo de energia, e o nível de conforto térmico provenientes da climatização artificial e da ventilação natural, respectivamente. As simulações foram realizadas em duas zonas bioclimáticas, na zona bioclimática 2 (ZB 2) e na zona bioclimática 8 (ZB 8), onde utilizou-se os arquivos climáticos da cidade de Camaquã e da cidade de Manaus, respectivamente. Com os resultados obtidos foi possível observar que a edificação com vidros eletrocrômicos apresentou melhor nível de conforto térmico nas horas ocupadas, e que o consumo de...
Molecular Crystals and Liquid Crystals, 2017
ABSTRACT Present work shows results of Li+ ions insertion and extraction from vanadium pentoxide ... more ABSTRACT Present work shows results of Li+ ions insertion and extraction from vanadium pentoxide doped with 5 mol% of molybdenum trioxide (V2O5:MoO3) thin films. The characterizations were performed by cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The obtained results revealed Li+ diffusional behavior for anodic and cathodic processes, and it was found that Li+ diffusion coefficient (D) values obtained from CV, PITT, and EIS varied from 10−10 to 10−12 cm2 s−1. Finally, a diffusion of Li+ process was modeled by solving Fick equation with constant D in plane sheet geometry.
Materials Research, 2019
Concrete is the most used material in the construction industry worldwide. Built concrete infrast... more Concrete is the most used material in the construction industry worldwide. Built concrete infrastructure is exposed to specific environments conditions during the asset's life, which impose chemical and physical actions that may lead to premature deterioration. Poor concrete durability and corrosion of reinforcement bars are the primary cause of structural deterioration and reduced service life. Most concrete deterioration mechanisms are driven by transport properties, in particular, the chloride diffusion coefficient. In this paper, the effect of curing in the chloride diffusion coefficient of conventional concrete is investigated through Electrochemical Impedance Spectroscopy (EIS). Reinforced concrete samples cured for 3, 7 and 28 days were exposed to accelerated chloride testing for 300 days (40 wet-dry cycles). Results indicate that the chloride diffusion coefficient reduces significantly with curing time, evidencing that prolonged curing may decrease the likelihood of corrosion in reinforced concrete structure when combined with appropriate design and construction processes.
Journal of Materials Science: Materials in Electronics, 2018
Cerium dioxide (CeO 2) and cerium dioxide doped with vanadium pentoxide (CeO 2 :V 2 O 5) were syn... more Cerium dioxide (CeO 2) and cerium dioxide doped with vanadium pentoxide (CeO 2 :V 2 O 5) were synthesized from sol-gel precursors and deposited by spin coating on a conductive glass substrate (FTO). The films with different concentration of dopant and number of deposited layers were studied throughout cyclic voltammetry (CV), chronoamperometry/chronocoulometry, atomic force microscopy (AFM), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The best value of charge density of 18.9 mC cm −2 was obtained for CeO 2 doped with 15 mol% of V 2 O 5 film. The chemical diffusion coefficient of lithium ions into CeO 2 was 1.73 × 10 −12 and CeO 2 :V 2 O 5 15 mol% 6.75 × 10 −13 cm 2 s −1. This film presented 79% of transparency in UV-Vis and 5% color change under ± 1.3 V of applied potentials. Structural analyses revealed its homogeneous surface and the root mean-squared roughness (RMS) value of 9.42 nm. Based on the obtained results, CeO 2 doped with 15 mol% V 2 O 5 film is a promising thin coating for the use in electrochromic devices as a passive counter-electrode.
Thin Solid Films, 2019
Electrochemical properties of WO3 sol-gel thin films on indium tin oxide/poly(ethylene terephthal... more Electrochemical properties of WO3 sol-gel thin films on indium tin oxide/poly(ethylene terephthalate) substrate, Thin Solid Films,
Molecular Crystals and Liquid Crystals, 2017
ABSTRACT Aiming to improve electrochromic properties of niobium pentoxide (Nb2O5) there were synt... more ABSTRACT Aiming to improve electrochromic properties of niobium pentoxide (Nb2O5) there were synthesized new, doped with lithium trifluoromethane sulfonate salt (LiCF3SO3), and vanadium pentoxide (Nb2O5:Li+:V2O5) thin films. A study of these films focused on influence of doping on the electrochromic performance of these films. It was observed that Nb2O5:Li+:V2O5 presents a reversible and fast insertion/extraction kinetics. A maximum charge density for three layers' film was −36.0 mC cm−2, and it corresponded to spectral transmission change of ΔT = 66%, i.e., variation from 80 to 20% from transparent to colored states.
Journal of Physics and Chemistry of Solids, 2018
The paper presents a systematic study of the electrochromic properties of thin films of V 2 O 5 :... more The paper presents a systematic study of the electrochromic properties of thin films of V 2 O 5 :TiO 2 for a possible utilization as counter-electrode in electrochromic devices. The V 2 O 5 :TiO 2 thin films were prepared by the sol-gel process and deposited on a substrate of fluorine-tin oxide transparent electrode (FTO) using the dip coating technique and heat treatment at 350 °C for 30 min. The films were characterized by chronocoulometry, cyclic voltammetry (CV), UV-Vis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), profilometry, and X-ray diffraction (XRD). The best results were obtained for the film of V 2 O 5 with 7.5 mol% of TiO 2 , which presented highest ion storage capacity of ~106 mC cm-2 and redox reversibility of 1. The diffusion of the Li + ions into the thin films was modeled by solving Fick equations with appropriate boundary conditions for a plane sheet geometry. Besides that, these films showed optical modulation of 35% at 633 nm after coloration and bleaching. The XRD patterns revealed that the films have an orthorhombic crystal structure; the AFM and the profilometry confirmed roughness and thickness of 16.76 and 617 nm, respectively.
Electrochimica Acta, May 1, 2019
Since 1980´s natural polymers are studied as sources for solid polymer electrolytes (SPEs) in opt... more Since 1980´s natural polymers are studied as sources for solid polymer electrolytes (SPEs) in opto-electronic equipment because of their abundance in the environment, inexpensiveness, and biological degradation characteristics. Xanthan gum is a naturally occurring polysaccharide found in the microbial world, and its main advantage is to produce transparent solutions with elevated viscosity and stability including wide range of temperature. Therefore, the present paper presents the FTIR and impedance study of xanthan gum as a host matrix for the ionically conducting membranes. Different contents of proton conducting species were incorporated into the polymer host and the membranes were realized by the method of solution casting. The FTIR results indicated that the electrolytes were formed by the polymeric network. The frequency independent conductivity response pointed the best dc conductivity values of 7.2610-5 to 3.9210-4 S.cm-1 , in the temperature range from 20 to 80 o C, for the sample with 2.00 g of acetic acid. The occurrence of the electrode polarization was interpreted by the combination of the complex dielectric permittivity (*), loss tangent (tan ), conductivity (), and complex electric modulus (M*).
Materials Research-ibero-american Journal of Materials, 2019
Concrete is the most used material in the construction industry worldwide. Built concrete infrast... more Concrete is the most used material in the construction industry worldwide. Built concrete infrastructure is exposed to specific environments conditions during the asset's life, which impose chemical and physical actions that may lead to premature deterioration. Poor concrete durability and corrosion of reinforcement bars are the primary cause of structural deterioration and reduced service life. Most concrete deterioration mechanisms are driven by transport properties, in particular, the chloride diffusion coefficient. In this paper, the effect of curing in the chloride diffusion coefficient of conventional concrete is investigated through Electrochemical Impedance Spectroscopy (EIS). Reinforced concrete samples cured for 3, 7 and 28 days were exposed to accelerated chloride testing for 300 days (40 wet-dry cycles). Results indicate that the chloride diffusion coefficient reduces significantly with curing time, evidencing that prolonged curing may decrease the likelihood of corrosion in reinforced concrete structure when combined with appropriate design and construction processes.
Journal of Electronic Materials, Jan 3, 2021
This paper presents a study of physical and electrochemical properties relevant to the lithium io... more This paper presents a study of physical and electrochemical properties relevant to the lithium ion diffusion process governing WO3 thin films electrochromic phenomenon. The films were prepared from a solution obtained by the sol–gel process and deposited via dip-coating. They were characterized by chronocoulometry, chronoamperometry and in and ex situ ultraviolet–visible spectroscopy during coloring/bleaching of the films. To analyze the experimental data, a mathematical model was applied considering a reaction kinetics controlled by the diffusion of ion pairs. The effects of the intercalation of Li+, Na+ and K+ ions was compared. Theoretical and experimental results for the current, charge density and absorbance profiles in function of time are included in this paper. The highest values obtained were η=29.98C/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}eta=29.98,textC/cm2\eta = 29.98\,{\text{C/cm}}^{2}eta=29.98,textC/cm2\end{document} for electrochromic efficiency, ΔT = 61.6% for optical modulation, Qi=81.78mC/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}Qi=81.78,textmC/cm2Q_{i} = 81.78\,{\text{mC/cm}}^{2}Qi=81.78,textmC/cm2\end{document} for charge density, and reversibility of coloring/bleaching in the range of 75–90%. X-Ray diffractometry measurements confirmed the amorphous structure of the films. Fourier transform infrared spectroscopy was employed to analyze the functional groups present in the films structure, while their topology was studied via atomic force microscopy. The collected results confirmed a relationship between the electrochromic and electrochemical reactions, definitively associating color change with cations injection and the reduction of W6+ to W5+.
Optical Materials, Jun 1, 2022
Materials Chemistry and Physics
Journal of The Electrochemical Society
Herein, we have developed a new biopolymer gel electrolyte based on xanthan, a material widely us... more Herein, we have developed a new biopolymer gel electrolyte based on xanthan, a material widely used in the food and pharmaceutical industry. The incorporation of the ionic liquids 1-butyl-2,3-dimethylimidazolium iodide (BMMI.I) and 1-ethyl-2,3-dimethylimidazolium iodide (EMMI.I) has significantly enhanced ionic conductivity by 136% and 181%, respectively. These ionic liquids possess a substantial permanent dipole moment, which can induce the alignment of other dipoles around them, through conformational changes. The interplay between the ionic liquid and the segmental motion of the polymer was investigated through temperature-dependent conductivity measurements using the Vogel-Tamman-Fulcher equation. Analysis of the complex dielectric (ε′and ε″) constants revealed the polarization effect of ionic species at the electrode/electrolyte interface. Additionally, the analysis of the complex electric modulus (M′and M″) and the loss tangent (tang δ) show that the incorporation of EMMI.I re...
Biomass Conversion and Biorefinery
Materials Research Bulletin, 2021
Abstract Thin films of cerium dioxide (CeO2) and cerium dioxide doped with vanadium pentoxide (Ce... more Abstract Thin films of cerium dioxide (CeO2) and cerium dioxide doped with vanadium pentoxide (CeO2:V2O5) were prepared through sol-gel route and spin coating deposition, for use as smart materials. This work evaluated films that underwent a weathering process in an accelerated weathering test chamber and the changes in their properties. The influence of the temperature was also studied electrochemically. Regarding the weathering process, there were variations in the charge insertion capacity during the investigated period. However, at the end of the 900 simulated days, the CeO2:V2O5 presented interesting values. For the EIS analyses, the curve (Nyquist plot) remained about 45° inclination, suggesting a diffusional process. The morphological and structural analyses demonstrated that by doping the film, occurs a reduction on the degradation, although the structure showed no changes. For different temperatures, the film becomes more resistive as the temperature increases. The chronocoulometry showed that the charge insertion capacity increases with temperature.
Ionics, 2022
The present study investigates the preparation and properties of solid polymer electrolytes based... more The present study investigates the preparation and properties of solid polymer electrolytes based on poly(vinyl alcohol) (PVA) and gum Arabic (GA). The Fourier transform infrared spectroscopy was used to demonstrate the interaction between PVA/GA and LiClO4 via -COO- and -OH functional groups and the electrochemical impedance spectroscopy to study the dielectric properties in a frequency range between 106 and 101 Hz and temperatures from 25 to 80 °C. This last revealed that the conductivity increases with the temperature, indicating an ion conduction and segmental movements of the polymer. Moreover, changes in the peak positions of the loss tangent at high frequencies indicated a decrease in relaxation time and an increase in ionic dynamics as a function of temperature. From the DC polarization, ion and electron transference numbers of PVA/GA24 were 0.997 and 0.003, respectively. Finally, long cyclic voltammetry (CV) cycle and thermal stability measures support that PVA/GA polymer electrolytes possess suitable characteristics for solid-state lithium-ion batteries or electrochemical double-layer capacitors.
This work aims to analyze the thermoenergetic and luminous performance of a building with office ... more This work aims to analyze the thermoenergetic and luminous performance of a building with office characteristic activities with electrochromic glasses through comparative study, considering common glasses of 3mm and 6mm. For the computational simulation were used the EnergyPlus software. Simulations were performed with the Clear common glass Clear of 3 mm and 6 mm and the electrochromic glass Sage Glass 9 mm with the purpose of analyzing the lighting, the energy consumption, and the level of thermal comfort coming from the artificial climatization and the natural ventilation, respectively. The simulations were performed in two bioclimatic zones, in bioclimatic zone 2 (ZB 2) and in bioclimatic zone 8 (ZB 8), where it was used the climate files from the city of Camaquã and the city of Manaus, respectively. With the results obtained it was possible to observe that the building with electrochromic glasses presented the best level of thermal comfort in the hours occupied, and that the en...
Journal of Electronic Materials, 2021
This paper presents a study of physical and electrochemical properties relevant to the lithium io... more This paper presents a study of physical and electrochemical properties relevant to the lithium ion diffusion process governing WO3 thin films electrochromic phenomenon. The films were prepared from a solution obtained by the sol–gel process and deposited via dip-coating. They were characterized by chronocoulometry, chronoamperometry and in and ex situ ultraviolet–visible spectroscopy during coloring/bleaching of the films. To analyze the experimental data, a mathematical model was applied considering a reaction kinetics controlled by the diffusion of ion pairs. The effects of the intercalation of Li+, Na+ and K+ ions was compared. Theoretical and experimental results for the current, charge density and absorbance profiles in function of time are included in this paper. The highest values obtained were η=29.98C/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}eta=29.98,textC/cm2\eta = 29.98\,{\text{C/cm}}^{2}eta=29.98,textC/cm2\end{document} for electrochromic efficiency, ΔT = 61.6% for optical modulation, Qi=81.78mC/cm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}Qi=81.78,textmC/cm2Q_{i} = 81.78\,{\text{mC/cm}}^{2}Qi=81.78,textmC/cm2\end{document} for charge density, and reversibility of coloring/bleaching in the range of 75–90%. X-Ray diffractometry measurements confirmed the amorphous structure of the films. Fourier transform infrared spectroscopy was employed to analyze the functional groups present in the films structure, while their topology was studied via atomic force microscopy. The collected results confirmed a relationship between the electrochromic and electrochemical reactions, definitively associating color change with cations injection and the reduction of W6+ to W5+.
Matéria (Rio de Janeiro), 2020
RESUMO Este trabalho tem como objetivo analisar o desempenho termoenergético e luminoso de uma ed... more RESUMO Este trabalho tem como objetivo analisar o desempenho termoenergético e luminoso de uma edificação com atividades características de escritórios com vidros eletrocrômicos através de estudo comparativo, considerando vidros comuns de 3mm e 6mm. Para a simulação computacional foi utilizado o programa EnergyPlus . Foram realizadas simulações com o vidro comum Clear 3mm e de 6mm e o vidro eletrocrômico Sage Glass 9mm com a finalidade de analisar a iluminação, o consumo de energia, e o nível de conforto térmico provenientes da climatização artificial e da ventilação natural, respectivamente. As simulações foram realizadas em duas zonas bioclimáticas, na zona bioclimática 2 (ZB 2) e na zona bioclimática 8 (ZB 8), onde utilizou-se os arquivos climáticos da cidade de Camaquã e da cidade de Manaus, respectivamente. Com os resultados obtidos foi possível observar que a edificação com vidros eletrocrômicos apresentou melhor nível de conforto térmico nas horas ocupadas, e que o consumo de...
Molecular Crystals and Liquid Crystals, 2017
ABSTRACT Present work shows results of Li+ ions insertion and extraction from vanadium pentoxide ... more ABSTRACT Present work shows results of Li+ ions insertion and extraction from vanadium pentoxide doped with 5 mol% of molybdenum trioxide (V2O5:MoO3) thin films. The characterizations were performed by cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The obtained results revealed Li+ diffusional behavior for anodic and cathodic processes, and it was found that Li+ diffusion coefficient (D) values obtained from CV, PITT, and EIS varied from 10−10 to 10−12 cm2 s−1. Finally, a diffusion of Li+ process was modeled by solving Fick equation with constant D in plane sheet geometry.
Materials Research, 2019
Concrete is the most used material in the construction industry worldwide. Built concrete infrast... more Concrete is the most used material in the construction industry worldwide. Built concrete infrastructure is exposed to specific environments conditions during the asset's life, which impose chemical and physical actions that may lead to premature deterioration. Poor concrete durability and corrosion of reinforcement bars are the primary cause of structural deterioration and reduced service life. Most concrete deterioration mechanisms are driven by transport properties, in particular, the chloride diffusion coefficient. In this paper, the effect of curing in the chloride diffusion coefficient of conventional concrete is investigated through Electrochemical Impedance Spectroscopy (EIS). Reinforced concrete samples cured for 3, 7 and 28 days were exposed to accelerated chloride testing for 300 days (40 wet-dry cycles). Results indicate that the chloride diffusion coefficient reduces significantly with curing time, evidencing that prolonged curing may decrease the likelihood of corrosion in reinforced concrete structure when combined with appropriate design and construction processes.
Journal of Materials Science: Materials in Electronics, 2018
Cerium dioxide (CeO 2) and cerium dioxide doped with vanadium pentoxide (CeO 2 :V 2 O 5) were syn... more Cerium dioxide (CeO 2) and cerium dioxide doped with vanadium pentoxide (CeO 2 :V 2 O 5) were synthesized from sol-gel precursors and deposited by spin coating on a conductive glass substrate (FTO). The films with different concentration of dopant and number of deposited layers were studied throughout cyclic voltammetry (CV), chronoamperometry/chronocoulometry, atomic force microscopy (AFM), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The best value of charge density of 18.9 mC cm −2 was obtained for CeO 2 doped with 15 mol% of V 2 O 5 film. The chemical diffusion coefficient of lithium ions into CeO 2 was 1.73 × 10 −12 and CeO 2 :V 2 O 5 15 mol% 6.75 × 10 −13 cm 2 s −1. This film presented 79% of transparency in UV-Vis and 5% color change under ± 1.3 V of applied potentials. Structural analyses revealed its homogeneous surface and the root mean-squared roughness (RMS) value of 9.42 nm. Based on the obtained results, CeO 2 doped with 15 mol% V 2 O 5 film is a promising thin coating for the use in electrochromic devices as a passive counter-electrode.
Thin Solid Films, 2019
Electrochemical properties of WO3 sol-gel thin films on indium tin oxide/poly(ethylene terephthal... more Electrochemical properties of WO3 sol-gel thin films on indium tin oxide/poly(ethylene terephthalate) substrate, Thin Solid Films,
Molecular Crystals and Liquid Crystals, 2017
ABSTRACT Aiming to improve electrochromic properties of niobium pentoxide (Nb2O5) there were synt... more ABSTRACT Aiming to improve electrochromic properties of niobium pentoxide (Nb2O5) there were synthesized new, doped with lithium trifluoromethane sulfonate salt (LiCF3SO3), and vanadium pentoxide (Nb2O5:Li+:V2O5) thin films. A study of these films focused on influence of doping on the electrochromic performance of these films. It was observed that Nb2O5:Li+:V2O5 presents a reversible and fast insertion/extraction kinetics. A maximum charge density for three layers' film was −36.0 mC cm−2, and it corresponded to spectral transmission change of ΔT = 66%, i.e., variation from 80 to 20% from transparent to colored states.
Journal of Physics and Chemistry of Solids, 2018
The paper presents a systematic study of the electrochromic properties of thin films of V 2 O 5 :... more The paper presents a systematic study of the electrochromic properties of thin films of V 2 O 5 :TiO 2 for a possible utilization as counter-electrode in electrochromic devices. The V 2 O 5 :TiO 2 thin films were prepared by the sol-gel process and deposited on a substrate of fluorine-tin oxide transparent electrode (FTO) using the dip coating technique and heat treatment at 350 °C for 30 min. The films were characterized by chronocoulometry, cyclic voltammetry (CV), UV-Vis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), profilometry, and X-ray diffraction (XRD). The best results were obtained for the film of V 2 O 5 with 7.5 mol% of TiO 2 , which presented highest ion storage capacity of ~106 mC cm-2 and redox reversibility of 1. The diffusion of the Li + ions into the thin films was modeled by solving Fick equations with appropriate boundary conditions for a plane sheet geometry. Besides that, these films showed optical modulation of 35% at 633 nm after coloration and bleaching. The XRD patterns revealed that the films have an orthorhombic crystal structure; the AFM and the profilometry confirmed roughness and thickness of 16.76 and 617 nm, respectively.