The Determination of Electrolyte Stability and Conditions for Electrochromic WO3 Films Deposition

The present research is devoted to finding the condition and intricacies of WO3 film electrodeposition from peroxotungstic acid-based electrolyte that can be used for real production process. For deposition of electrochromic WO3 films, the galvanostatic regime with following parameters is proposed: cathodic current density -0.2 mA/cm2, deposition time 30 min. The films prepared under such deposition parameters are transparent and had good adhesion to the substrate – the glass coated with fluorine-doped tin oxide. The averaged coloration degree for film deposited from fresh electrolyte is 10%, while for film deposited from regenerated electrolyte – 5 %. During investigation, the potential window in which WO3 film could be colored and bleached, without reduction of SnO2 to metallic tin is established. It is also demonstrated that electrolytes containing peroxotungstic acid are unstable and degrade over time. It is proposed to use hydrogen peroxide for regeneration of electrolyte. It is demonstrated that electrolyte can be partially regenerated with hydrogen peroxide

Influence of Temperature on the Characteristics of Ni(II), Ti(IV) Layered Double Hydroxides Synthesised by Different Methods

The influence of temperature on the characteristics of Ni(II)–Ti(IV) LDH was investigated in the work.Ni(II)–Ti(IV) layered double hydroxides were synthesized from a solution of Ni2+ and Ti4+ with the cationic ratio of Ni2+/Ti4+=5 by using three coprecipitation techniques: titration, coprecipitation at high supersaturation and homogeneous coprecipitation. The prepared samples were characterized by means of X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC).By means of XRD, it was revealed that all samples prepared using titration and coprecipitation at high supersaturation at 65 and 20 oC correspond to Ni-Ti LDH structure. Elevated temperature during sample preparation using titration and coprecipitation at high supersaturation did not have a significant effect on phase composition, but affected the crystallinity. According to XRD results, the sample prepared using homogeneous coprecipitation at 70 oC had a significant content of b-Ni(OH)2. Increasing the synthesis temperature to 80 oC has led to the almost complete disappearance of b-Ni(OH)2 reflections.By means of TGA and DSC, it was found that titration method leads to formation of samples with higher thermal stability than those prepared by high supersaturation. Elevated temperature and hydrothermal treatment leads to higher thermal stability of the samples. Samples prepared by homogeneous coprecipitation show complicated behavior during thermal decomposition, confirming the presence of cyanate ions in the interlayer gallery