Electrochromism is a phenomenon of reversible color change when an external voltage is applied, causing an electrochemical redox reaction. This interesting property leads to the development of several technological applications, such as electronic papers, rear-view mirrors and smart windows. A typical electrochromic device coating is a multi-layer device consisting of an active electrochromic electrode, a counter electrode, an electrolyte layer separating the two electrodes, and two transparent conducting layers serving as electrical leads. A key requirement in developing an electrochromic electrode is to increase the amount of reaction sites of the electrode.
In this work, we report a facile and cost efficient preparation of electrochromic electrode which are formed by assembly of nano-sized clusters of nickel oxides by electrodeposition integrating amino acids. This nanostructured nickel-oxide film with interconnected clusters benefits electrolyte penetration and provide large surface area for charge-transfer reactions. Here, we show that the integration of amino acids resulted in increased nickel-oxide film thickness compared to the system without amino acids. Moreover, the nickel-oxide film also shows a remarkably enhanced electrochromic performance compared to the blank nickel sample. These results demonstrate that the thickness of electrodeposited nickel oxide film thickened with increased reaction site. A three-dimensional (3D) electrochromic material with many reaction sites is achieved. Further, the thickness of electrodeposited nickel oxide film can be tuned by altering kinds of amino acids.