Aiming at enhancing the electrochromic properties of anodically colored NiO thin films, lithium doped NiO thin films were grown on FTO/glass substrates, by the pulsed laser deposition (PLD) method. ...Optimized conditions, namely a room temperature substrate under 10Pa oxygen pressure were used. Comparison with undoped NiO thin films indicates that lithium doping deteriorates NiO cubic phase (111) preferred orientation and also induces lattice disorder. The investigation of the electrochromic properties of Li–Ni–O thin films in aqueous liquid electrolyte, 1M KOH, on the one hand and in hydrophobic lithium conductive ionic liquid, 0.3M LiTFSI in BMITFSI, on the other hand, demonstrates an improvement in the electrochromic performances with lithium doping. Finally, electrochromic devices built on the association of WO3 and Li–Ni–O thin films and using the above quoted ionic liquid blended with PMMA as electrolyte are reported. Good electrochromic performances and neutral color are shown.
Natural molecular dye, anthocyanin, is described here as safe sensitizer for TiO2 particles in photo-degradation of organic contaminants in water. The dye is a promising replacement for the more ...costly and hazardous heavy metal based systems, such as CdS particles and Ru-compounds. TiO2/anthocyanin effectively catalyzed the photo-degradation of methyl orange contaminant under solar simulator radiation. The new TiO2/anthocyanin catalyst showed comparable efficiency to earlier systems, while avoiding their hazardous nature. When supported onto activated carbon (AC) particles, the resulting AC/TiO2/anthocyanin system showed enhanced efficiency and ease of recovery from the catalytic reaction mixture. The natural dye molecules showed the tendency to degrade under photo-degradation conditions, just like earlier hazardous sensitizers. However, complete mineralization of anthocyanin occurred leaving no traces of organic species in solution. Sensitizer degradation caused deactivation of the supported catalyst on recovery. Such a shortcoming was overcome by re-treatment of the recovered catalysts with fresh dye. Effects of different reaction parameters on the catalyst efficiency were studied. A mechanism, similar to earlier CdS-sensitized catalyst systems, is proposed for the TiO2/anthocyanin catalyst.
Electrochromic nickel oxide (Ni1−xO) pigment powder which was made from nickel acetate reacting with H2O2/urea solution followed by heat treatment of xerogels at 400°C (24h) was milled with zirconia ...beads in pure water or water with added nickel oxyhydroxy precipitate acting simultaneously as the dispersant and the coating binder. The corresponding pigment particle suspensions were spin coated on FTO glass and flexible ITO-PET foils, respectively, and cured at 150°C. The optical properties of the deposited pigment coatings on FTO glass substrates were determined with an UV VIS spectrometer, providing total direct transmittance (TT), total diffuse transmittance (DT) and haze (in %). Haze increased with the coating thickness but did not exceed 4%. SEM micrographs of the deposited pigment coatings revealed that they consisted of agglomerated Ni1−xO pigment with voids.
Potential cycling of Ni1−xO pigment coatings and Ni1−xO thin films was performed in 1M LiClO4/PC and 0.1M TBA+ triflate/PC electrolytes, revealing that the pigment coatings exhibited electrochemical and electrochromic activity also in lithium free (aprotic) electrolyte, while variations of the oxidation and reduction reaction peaks at various scan rates confirmed the presence of surface electrochemical reactions. The near-grazing incidence angle reflection–absorption spectroscopic technique (IR RA) was employed for identifying surface and inner-grain Ni–O stretching modes, the former being responsible for observed electrochemical properties, which was also demonstrated from the ex situ IR RA measurements performed for coatings charged/discharged in 1M LiClO4/PC and 0.1M TBA+ triflate/PC electrolytes. The results disclosed in this study suggest that the electrochromic effect was not in direct correlation with the de-insertion/insertion of small ions into the NiO (bunsenite) grains but rather the pigment coatings behave similarly to nickel oxide electrochemical capacitors. The electrochromic response of a flexible EC devices made either of PEDOT (self-standing foil) or WO3 and Ni1−xO pigment coatings glued with PMMA based electrolytes without and with lithium salt were recorded for the demonstration of the possible practical application of wet deposited Ni1−xO pigment coatings made as “electrochromic” paints.
Schematic presentation of PEDOT/solid lithium-free electrolyte/Ni1−xO EC device and the corresponding EC response. Display omitted
•EC paint made of pre-prepared Ni1−xO pigment used for pigment coating deposition.•IR spectra distinguished between the Ni–O grain (G ωLO) and surface (IG ωLO) modes.•Ni1−xO coatings showed EC effect also in lithium-free electrolytes.•Color/bleaching associated with surface reactions.•Flexible EC devices (PEDOT or WO3 with Ni1−xO) were constructed.
Natural molecular dye, anthocyanin, is described here as safe sensitizer for TiO
2 particles in photo-degradation of organic contaminants in water. The dye is a promising replacement for the more ...costly and hazardous heavy metal based systems, such as CdS particles and Ru-compounds. TiO
2/anthocyanin effectively catalyzed the photo-degradation of methyl orange contaminant under solar simulator radiation. The new TiO
2/anthocyanin catalyst showed comparable efficiency to earlier systems, while avoiding their hazardous nature. When supported onto activated carbon (AC) particles, the resulting AC/TiO
2/anthocyanin system showed enhanced efficiency and ease of recovery from the catalytic reaction mixture. The natural dye molecules showed the tendency to degrade under photo-degradation conditions, just like earlier hazardous sensitizers. However, complete mineralization of anthocyanin occurred leaving no traces of organic species in solution. Sensitizer degradation caused deactivation of the supported catalyst on recovery. Such a shortcoming was overcome by re-treatment of the recovered catalysts with fresh dye.
Effects of different reaction parameters on the catalyst efficiency were studied. A mechanism, similar to earlier CdS-sensitized catalyst systems, is proposed for the TiO
2/anthocyanin catalyst.
Display omitted
Electrochromic (EC) performances of Ni3+ containing NiO thin films, called modified NiO thin films, prepared either by pulsed laser deposition or by chemical route are reported. When cycled in ...lithium based electrolyte, the comparison of the EC behavior of nonstoichiometric NiO thin films points out a larger optical contrast for the films synthesized by chemical route with the absence of an activation period on early electrochemical cycling due in particular to a larger porosity. Herein we demonstrate faster kinetics for modified NiO thin films cycled in lithium ion free electrolyte. Finally, X-ray absorption spectroscopy is used for a preliminary understanding of the mechanism involved in this original EC behavior linked to the film characteristics including their disorder character, the presence of Ni3+ and their porous morphology.
•Nonstoichiometric NiO thin films•Electrochromic performances in lithium free electrolyte•X-ray absorption spectroscopy investigation of as-deposited films and upon cycling
Electrochromic nickel oxide (Ni1 subxO) pigment powder which was made from nickel acetate reacting with Hsub 2Osub 2/urea solution followed by heat treatment of xerogels at 400 C was milled with ...zirconia beads in pure water or water with added nickel oxyhydroxy precipitate acting simultaneously as the dispersant and the coating binder. The corresponding pigment particle suspensions were spin coated on Ff0 glass and flexible ITO-PET foils, respectively, and cured at 150 C. The optical properties of the deposited pigment coatings on FTC glass substrates were determined with an UV VIS spectrometer, providing total direct transmittance, total diffuse transmittance (DT) and haze. The electrochromic response of a flexible EC devices made either of PEDOT or WOsub 3 and Nisub 1 subxO pigment coatings glued with PMMA based electrolytes without and with lithium salt were recorded for the demonstration of the possible practical application of wet deposited Nisub 1 subxO pigment coatings made as "electrochromic" paints.
Ce travail de thèse a été réalisé dans le cadre du programme européen INNOSHADE, dont l’objectif était la réalisation de dispositifs électrochromes à coloration neutre. Cette coloration neutre est le ...résultat de l’association dans un même dispositif de la couleur marron de films à base d’oxyde de nickel avec celle bleue de films d’oxyde de tungstène ou de PEDOT. Nos recherches ont été orientées vers des films minces d’oxyde de nickel modifié contenant des ions nickel trivalent, alliant porosité et désordre structural. Deux techniques de dépôt ont été utilisées : l’ablation laser et le trempage-retrait (dip-coating). Des processus de coloration et de décoloration de ces films en milieux liquides ioniques hydrophobes lithiés et non lithiés, faisant intervenir la participation d’anions tels que TFSI-, ont été mis en évidence pour la première fois dans cette thèse. Les dispositifs tout solides correspondants présentent des efficacités optiques élevées et une bonne durabilité.
Electrochromic devices, ECDs, are able to change their optical properties under an applied voltage. In the framework of the European project INNOSHADE, the aim of the current work is the development of neutral color ECDs based on nickel oxide thin films as counter electrode. Ni3+ containing NiO thin films, called modified NiO thin films, were deposited both by Pulsed Laser Deposition and chemical route. When cycled in lithium based electrolyte, the comparison of the EC behavior of non-stoichiometric NiO thin films points out a higher electrochemical capacity associated with a larger optical contrast for the films synthesized by chemical route due in particular to a larger porosity. Highlighting a novel approach, herein we demonstrate faster kinetics for modified NiO thin films cycled in lithium ion free electrolyte and suggest the participation of anions. High electrochromic efficiency and nice durability of all-solid state devices associating modified NiO and WO3 or Poly(3,4 –ethylenedioxythiophene) PEDOT layers are reported.
Ce travail de thèse a été réalisé dans le cadre du programme européen INNOSHADE, dont l'objectif était la réalisation de dispositifs électrochromes à coloration neutre. Cette coloration neutre est le ...résultat de l'association dans un même dispositif de la couleur marron de films à base d'oxyde de nickel avec celle bleue de films d'oxyde de tungstène ou de PEDOT. Nos recherches ont été orientées vers des films minces d'oxyde de nickel modifié contenant des ions nickel trivalent, alliant porosité et désordre structural. Deux techniques de dépôt ont été utilisées : l'ablation laser et le trempage-retrait (dip-coating). Des processus de coloration et de décoloration de ces films en milieux liquides ioniques hydrophobes lithiés et non lithiés, faisant intervenir la participation d'anions tels que TFSI-, ont été mis en évidence pour la première fois dans cette thèse. Les dispositifs tout solides correspondants présentent des efficacités optiques élevées et une bonne durabilité.
