The study of activation impact during formation and testing of Ni(OH)2 electrochromic films in the presence of Al3+ and WO42- ions

Abstract

The present study is devoted to an attempt to improve the characteristics of nickel hydroxide electrochromic films. The study of optical and electrochemical characteristics of the films, prepared through the codeposition of nickel and aluminum and additional modification during the cycling of the prepared samples was conducted. The modification was realized through the cycling of films in the solution of potassium hydroxide with small amounts of potassium tungstate. Over the course of the study, a series of films were obtained, which demonstrated different electrochemical and optical behavior. Thus, it was found that both the deposition method and the cycling regime have a significant effect on the characteristics of electrochromic films. It is shown that for the potentiodynamic regime, the best characteristics were demonstrated by the film without modifications or additives. On the other hand, all modified films, codeposited with aluminum, demonstrated better characteristics in galvanostatic regimes over the reference film. It would appear that this is due to the physico-chemical features of the films deposited in the presence of additives. In turn, the use of high-rate cycling regime leads to a decrease of electrochromic characteristics, namely higher degree of irreversibility. Despite the difference of currents in different galvanostatic regimes by 4 times, the coloration degree did not differ much. It was also found that the presence of 0.3 mM potassium tungstate in the cycling electrolyte resulted in a significant decrease in the electrochromic properties of the samples