Manufacturing of flexible electrochromic (EC) devices requires the use of low-temperature films for deposition on electronically conductive foils. With this aim, low-temperature V-oxide films were ...spin-coated from a dispersion prepared by milling of crystalline V2O5 powder in vanadium(V) tri-n-propoxide oxide/isopropanol sol as dispersant. TEM images showed that the milling procedure enables the introduction of some V2O5 nanocrystallites into the matrix of the V-oxide pigmented film prepared at 150 °C. The electrochromic properties were analyzed using in situ UV–visible absorbance spectroelectrochemistry. The low transmittance values of as-prepared pigmented films revealed the presence of a greater amount of reduced V4+ centers compared to the crystalline sol-gel V2O5 model films. Significant bleaching of pigmented V-oxide films occurred during subsequent 521 cycles in the safe potential range.
Three different types of vibrational spectroscopies were applied to examine the powdered V-oxide film, and the results were compared to the band changes for the sol-gel crystalline V2O5 films. For initial films, the modes in the IR reflection-absorption spectra were systematically shifted to higher wavenumbers with regard to the modes in the IR absorbance spectra. Both IR techniques confirmed the reversible shift of the vanadyl V-OA band to lower frequencies and the disappearance of the bridging V-OB-V mode upon intercalation. Raman spectra showed the appearance of two vanadyl stretching modes at 986 and 961 cm−1 that occurred simultaneously with the decrease in the intensity of the bands in the 750–400 cm−1 spectral region. After the deintercalation, the Raman spectra of the low-temperature films showed broad bands that remained after the second bleaching. Finally, a flexible NiO1-x/ormolyte/V-oxide EC device was constructed. The device was composed of two different pigmented films and demonstrated the practical applicability of the low-temperature pigmented films.
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•Low-temperature pigmented V-oxide films with nanocrystalites of V2O5 were fabricated.•V4+ was also present in V-oxide films that were bleached during the cycling.•Ex situ IR reflection-absorption, IR absorption and Raman spectroscopy were applied.•Vibrational properties of pigmented V-oxide were compared to those of crystalline V2O5.•A flexible Ni1-xO/ormolyte/V-oxide EC device was fabricated using two types of pigmented films.
Stable function of hybrid electrochromic devices (ECDs) is achieved by the application of quasi-solid-state redox electrolytes with high ionic conductivity and electrochemical stability. For this ...purpose, a polymeric gel electrolyte based on an imidazolium ionic liquid (IL)-functionalized siloxane network is prepared. First, a sol-gel processable, bis end-capped trialkoxysilyl-functionalized imidazolium-based IL is synthesized. The characteristics of the IL enable solvolysis and condensation on both ends of the molecule. In this way, the crosslinked IL forms a firm and brittle gel, as confirmed by IR and 29Si NMR analyses. The addition of iodine for I−/I3− redox pair formation does not produce a gel with sufficiently high ionic conductivity for ECD assembly. To obtain a more conductive gel electrolyte with an ionic conductivity of the order of magnitude 10−3 S cm−1, a nonreactive, 1-methyl-3-propyl imidazolium iodide IL is added as the cosolvent. These redox electrolytes with different concentrations of iodine are tested in hybrid EC devices for ~11,000 cycles. All the devices reveal an increase in lightness with cycling, either for the bleached or colored states, which occur due to gradual transformation of I5− to I3− and I− species. In situ Raman spectroelectrochemistry is applied to gain insight into the ECDs during 1250 cycles of functioning and enables the various iodide species to be differentiated.
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•Bis end-capped trialkoxysilyl-functionalized imidazolium ionic liquid (IL) was synthesized.•Sol-gel processes enabled the formation of a solidified I−/I3− redox electrolyte.•Siloxane-IL redox electrolytes with different polyiodide compositions were formed.•Stable hybrid electrochromic devices with 11,000 coloring/bleaching cycles were produced.•In situ Raman allowed insight into the devices during functioning (the 12th and the 1250th cycles).
Sulfur-doped TiO2 (S-TiO2) composites with reduced graphene oxide (rGO), wt. % of rGO equal to 0.5%, 2.75%, and 5.0%, were prepared by a one-pot solvothermal procedure. The aim was to improve ...photocatalytic performance in comparison to TiO2 under simulated solar irradiation for the treatment of diclofenac (DCF) in aqueous medium. The obtained composites were characterized for physical-chemical properties using thermogravimetric analysis (TGA), X-ray diffractograms (XRD), Raman, scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), Brauner Emmett Teller (BET), and photoluminescence (PL) analyses, indicating successful sulfur doping and inclusion of rGO. Sulfur doping and rGO have successfully led to a decrease in photogenerated charge recombination. However, both antagonistic and synergistic effects toward DCF treatment were observed, with the latter being brought forward by higher wt.% rGO. The composite with 5.0 wt.% rGO has shown the highest DCF conversion at pH 4 compared to that obtained by pristine TiO2, despite lower DCF adsorption during the initial dark period. The expected positive effects of both sulfur doping and rGO on charge recombination were found to be limited because of the subpar interphase contact with the composite and incomplete reduction of the GO precursor. Consequent unfavorable interactions between rGO and DCF negatively influenced the activity of the studied S-TiO2/rGO photocatalyst under simulated solar irradiation.
Spectroelectrochemistry can offer important insights into the performance of materials that change properties during electrochemical treatment. The benefits of spectroelectrochemical measurements are ...shown through the example of an electrochromic sol–gel vanadium(V) oxide (V
2
O
5
) film. In situ UV-visible absorbance spectroelectrochemistry is indispensable to reveal the optical modulation, which reached about 28% during the first coloration in the unsafe potential range, but then diminished to around 12% during the following cycles. Ex situ IR and Raman spectroscopy were used to probe the structural modifications that occur during the intercalation of small ions into the orthorhombic structure of the crystalline V
2
O
5
film. In particular, infrared reflection–absorption (IR RA) and IR absorption spectroelectrochemistry confirmed the red shift of the vanadyl band and the disappearance of the bridging oxygen band due to the puckering of layers of VO
5
square pyramids following intercalation. In addition, Raman spectra reveal the broad and low-intensity bands of the V
2
O
5
film after it has been coloured in the unsafe potential range. Electron energy-loss spectroscopy (EELS) revealed the presence of vanadium in oxidation states V
4+
, V
4+
/V
5+
, and V
5+
on different positions on the bleached film.
Highlights
Vibrational and UV-visible spectroelectrochemistry of sol–gel electrochromic V
2
O
5
films.
In situ UV-visible absorbance of V
2
O
5
film defines its optical modulation.
Ex situ IR reflection–absorption, IR absorption during coloration and bleaching.
Ex situ Raman reveals significant band changes in the unsafe potential range.
Ex situ EELS spectra confirm V
4+
, V
4+
/V
5+
, and V
5+
sites on the bleached film.
The number of commercial products claiming self-cleaning properties is rising and testing of long-term activity and durability of such coatings needs to be addressed more. The time-dependent changes ...of different characteristics like haze, transparency, and color are essential for transparent glazing materials. Herein, we aimed to examine whether the laboratory results obtained on the Zr-modified-titania-silica (TiZr) self-cleaning materials would translate to larger-scale outdoor-exposed testing. TiZr thin films were deposited via spraying onto float glass window surfaces and exposed into three different environments for 20 months. For comparison, a commercially available active SGG BIOCLEANTM glass and standard float glass were simultaneously exposed in the same conditions. It was shown that the self-cleaning property of either a commercial product or TiZr-coated float glass was not considerably effective in real field test conditions, although the previous laboratory tests showed pronounced photocatalytic activity of TiZr thin films. The inclination angle; however, was shown to have a considerable effect on the self-cleaning ability of samples, as did the rain patterns during the testing period. On the other hand, the anti-fogging effect of our TiZr material was very well expressed in controlled laboratory conditions (measuring droplet formation time) as well as in the real outdoor environment.
Two types of innovative coatings based on fluoroethylene/vinylether alternating copolymers are investigated as protective systems for bronze works-of-art. The influence of a polyhedral oligomeric ...silsesquioxane (POSS), i.e. open-cube trisilanol-heptaisooctyl-POSS, on the surface, mechanical, optical and electrochemical properties of coatings is examined. It is found that the isooctyl groups in the organic shell of POSS cause an increase in the hydrophobicity of the surface. On the other hand, nanoindentation tests show that the reduced modulus, hardness and plasticity index decrease with the addition of POSS, while abrasion resistance is slightly improved. Haze of coatings increases when POSS nanoparticles are present. More importantly, a beneficial effect of POSS addition on the protective efficiency against corrosion is assessed by exposure of coatings to acidic vapours and electrochemical treatments. In this regard, potentiodynamic polarisation clearly shows that the protective efficiency is systematically larger for coatings comprising POSS. The ex situ IR reflection-absorption spectroelectrochemistry shows that cuprous oxide can eventually form at the coating|bronze interface, which is identified through the spectroelectrochemistry of unprotected bronze.
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•Combination of protective efficiency and removability in anticorrosion coatings suitable for conservation of bronze.•Homogeneous distribution of POSS nanoparticles in fluoroethylene/vinylether-based coatings.•Cuprous oxide may form at the bronze|coating interface at high anodic potentials.•POSS nanoparticles addition enhanced hydrophobicity and protective efficiency while decreasing mechanical properties.
Versatile product protective coatings that deliver faster drying times and shorter minimum overcoat intervals that enable curing at faster line speeds and though lower energy consumption are often ...desired by coating manufacturers. Product protective coatings, based on silsesquioxane-modified diglycidyl ether of bisphenol-A (DGEBA) epoxy resin, are prepared through a glycidyl ring-opening polymerization using dicyandiamide (DICY) as a curing agent. As silsesquioxane modifier serves the octaglycidyl-polyhedral oligomeric silsesquioxane (GlyPOSS). To decrease the operational temperature of the curing processes, three different accelerators for crosslinking are tested, i.e.,
-benzyl dimethylamine, 2-methylimidazole, and commercial Curezol 2MZ-A. Differential scanning calorimetry, temperature-dependent FT-IR spectroscopy, and rheology allow differentiation among accelerators' effectiveness according to their structure. The former only contributed to epoxy ring-opening, while the latter two, besides participate in crosslinking. The surface roughness of the protective coatings on aluminum alloy substrate decreases when the accelerators are applied. The scanning electron microscopy (SEM) confirms that coatings with accelerators are more homogeneous. The protective efficiency is tested with a potentiodynamic polarization technique in 0.5 M NaCl electrolyte. All coatings containing GlyPOSS, either without or with accelerators, reveal superior protective efficiency compared to neat DGEBA/DICY coating.
Coatings based on organic-inorganic hybrids may effectively improve the resistance of metals/alloys against corrosion. In this work the protection ability of a coating based on ...(3-mercaptopropyl)trimethoxysilane (MPTMS) deposited on the well-known aluminium AA 2024 alloy is studied. The hydrolysis and condensation reactions in the initial sol and the structure of thermally treated protective MPTMS coatings is studied using infrared absorbance spectroscopy. In addition, the structure of coatings is investigated using infrared reflection-absorption (IR RA) spectroscopy. Several physical properties of prepared coatings such as contact angles, surface energy and thickness are reported. The corrosion protection ability of once, twice and three times deposited MPTMS coatings is studied using potentiodynamic polarisation measurements. Finally, possible morphological changes at different potentials of interest are investigated using in situ electrochemical AFM.
This work is licensed under a Creative Commons Attribution 4.0 International License .
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•Novel bis end-capped ethoxysilylpropyl-thioureido-fuctionalised PDMS precursor was synthesised.•Addition of trisilanol-heptaisooctyl-POSS increased protective efficiency.•Extensive ...IR spectroscopy confirmed hydrolysis and condensation processes.•Raman imaging enabled the determination of homogeneity of coatings.•In situ Raman spectroelectrochemical measurement was applied.
The aim of this work was to investigate the protective behaviour of bis-(3-(3-(3-triethoxysilyl)propyl)thioureido)propyl terminated polydimethylsiloxane (PDMSTU) pre-treatment coatings on the AA 2024 aluminium alloy. The silane solution was modified by the addition of bis-(3-(triethoxysilyl)propyltetrasulphide) (BTESPT) and trisilanol-heptaisooctyl-POSS (TS-iOc7-POSS) in order to introduce better crosslinking and improved mechanical and electrochemical stability in the silane primer coating. The corrosion behaviour of the protected AA 2024 alloy was studied during immersion in 0.5M NaCl solution, using potentiodynamic polarisation measurements and eventual structural changes were followed using in situ Raman spectroelectrochemical technique. The electrochemical experiments showed that the presence of BTESPT and TS-iOc7-POSS molecules improves the protective behaviour of the silane coating, while Raman imaging was used to determine their distribution in coatings.
Herein protective coatings against corrosion are compared with regard to their protective efficiency. The coatings had been prepared over the course of time from differently ...trialkoxysilyl-functionalized commercial or synthesized precursors but were tested using the same techniques and in similar conditions. The coatings are compared according to the existing data on contact angles for water, free surface energy, thickness and protective efficiency, expressed in term of corrosion current density. Moreover, the influence of differently functionalized trialkoxysilyl precursors on the crosslinking of coatings is regarded. It was also noted that too hydrophobic additives can introduce certain defects which can detrimentally influence the protective efficiency. Spectroelectrochemical approach can give important insights into the degradation of protective coatings under electrochemically induced loads.
infrared reflection-absorption (IR RA) spectroelectrochemical approach can identify hydration, breakage of some siloxane bands or changes in the C–H spectral region. Careful examination can confirm the interruption of some bands between alloy and coating that are responsible for its adhesion. Raman imaging is appropriate to follow the formation and growth of pits that form in the coatings.
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