Abstract
As a result of conducted studies, a series of electrochromic Ni(OH)2 films were prepared using the cathodic template method under the same conditions. Prepared films have been used for comparison of regimes for coloration-bleaching cycling. Main qualitative characteristics were also evaluated – averaged absolute coloration degree, averaged irreversibility on bleaching and visual comparison in the colored state after cycling.To compare the influence of different regimes, potentiodynamic, galvanostatic and complex regimes were proposed. For potentiodynamic regimes, different upper and lower potential limits were chosen. Initial current density for galvanostatic and complex regimes was chosen based on the results of the cyclic voltamperometry curve. Chosen current density was equal to the cathodic peak value on the fifth cycle of the cyclic voltamperometry curve recorded in the following regime: potential window [201–751 mV], scan rate 1 mV/s.Coloration-bleaching cycling in different regimes revealed high effectiveness of potentiodynamic regimes which showed the highest coloration degree of the films. On the other hand, it was found that narrowing and widening of potential windows relative to optimal resulted in worse characteristics of electrochromic films. Galvanostatic regimes showed the most optimal results in terms of absolute coloration degree and time required for coloration/bleaching. Complex regimes demonstrated the worst results. Theses regimes resulted in significant irreversibility and average rate of coloration and bleaching.Galvanostatic and complex regimes revealed the presence of two plateaus on the current density curves, which indicates the presence of both α-Ni(OH)2 and β-Ni(OH)2 in electrochromic material
Highlights
The modern world is facing the problem of depleting energy resources
For potentiodynamic regime Potentiodynamic No 4 (P4), the potential window was reduced to E [+351; +751 mV]
The optimal regimes for electrochromic and electrochemical characteristics and time required per cycle are: а) galvanostatic regime Galvanostatic No 12 (G1): Iа=+ICP, τA=50 s; IC=–ICP, τC=50 s; b) galvanostatic regime Galvanostatic No 23 (G2): Iа=+2ICP, τA=25 s; IC=–2∙ICP, τC=25 s. 3
Summary
The modern world is facing the problem of depleting energy resources. The problem can be solved in two ways: employment of new energy sources or/and lowering of energy consumption by utilizing so-called “smart” technologies. One promising division of “smart” technology is “smart” windows These devices can dynamically change their optical characteristics – color, transparency, glossiness. This allows for significant cost savings on air conditioning and lighting and reducing loads on power grids at peak consumption times [1]. Insufficient transparency, constant current consumption in one of states and high cost of used active element types limit their application. Power consumption only for state switch and potentially lower cost result in high chances for adoption. Despite such chances, a few factors limit their application. Reaction (1) is reversed upon cathodic polarization, and colored NiOOH transforms back into transparent Ni(OH)
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