Technical development leads to increasing power consumption. In such situation, the lack of energy problem could be solved by using "smart" devices. One of the types of the smart devices is so-called "Smart windows". These devices could change their optical parameters depending on current quantity and polarity.
Inorganic electrochemical electrochromic materials have a great potential. One of them – is a nickel hydroxide electrochromic film (NHEF). High colorization efficiency, material's low price, potentially high working resource are advantages for Ni(OH)2-based electrochromic systems.
Cathodic template deposition of nickel hydroxide films is considered as method for precipitation NHEF with high electrochemical, optical and physiochemical characteristics [1 – 3]. As template in the cathodic template deposition method polyvinyl alcohol is used. The viscosity of solutions for electrodeposition is much higher than those for pure water solutions. Furthermore, nickel nitrate dilute solution is used for uniform Ni(OH)2 distribution in case of FTO coated glass for electrodeposition. These two factors could influence on final properties of NHEF.
In order to improve agitation processes on microlevel ultrasonic radiation during electrodeposition process was used. For comparison, the Ni(OH)2 film without ultrasonic radiation during electrodeposition was obtained. Precipitation conditions are represented in table 1.
|Sample name||Solution||Solution temperature||Deposition time||ic||Ultrasonic radiation|
|CTD||0.01 Ni(NO)2, 5 % PVA*||30 °C||10 min||0.1 mA/cm2||-----|
|CTDus||0.01 Ni(NO)2, 5 % PVA*||30 °C||10 min||0.1 mA/cm2||42.5 kHz, 50 W|
PVA* – polyvinyl alcohol
In figure 1a cyclic voltammogram for CTD and CTDus samples is shown. As it seen, for sample that was electrodeposited at the presence of ultrasound, electrochemical characteristics are better. The current values are greater than those for sample deposited without ultrasonic radiation. Also, for both samples photographing in colored state were done – figure 1b. Comparison of images for CDT and CDTus samples showed that sample CDTus had more uniform and deeper colorization state.
Figure 1 – Cyclic voltammogram of CTD and CTDus samples (a); CTD (left) and CTDus (right) samples in colored state (b)
These facts could be explained by ultrasonic radiation influence on electrolyte. It is well known fact, that ultrasound in galvanic processes increase working currents due to agitation increasing in diffusion layer. Most likely, ultrasound has same influence especially in diluted solutions with high viscosity that is used for Ni(OH)2 electrodeposition.
- Kotok, V.A., Kovalenko, V.L., Ananchenko, B.A., Levko, E.N. (2014) The deposition of electrochromic film based on nickel hydroxide by electrochemical method XV International scientific conference «New Technologies and achievements in metallurgy, materials engineering and production engineering». Materials Engineering, Czestochowa, Poland, Collective Monografie, Р. 448 – 452
- Kotok, V.A., Malahova, E.V., Kovalenko, V.L., Baramzin, M.N., Kovalenko, P.V. (2016) Smart windows: cation internal and anion external activation for electrochromic films of nickel hydroxide. International forum for science and engineering students (IFSES), Guadalajara, Mexico, 2016: DOI: 10.13140/RG.2.2.33280.84486
- Kotok, V.A., Kovalenko, V.L., Zemlianiy, V.K. (2016) Electrochemical deposition of multilayered electrochromic thin films for smart windows. International forum for science and engineering students (IFSES), Guadalajara, Mexico, 2016: DOI: 10.13140/RG.2.2.25201.89441