Bias-dependent optical and ion incorporation properties of CoAl-layered double hydroxides

Layered double hydroxides (LDHs) have received much attention because of their various applications such as energy storage, catalyst, biological, and sensing materials due to a wide variety of advantages and unique physical properties. However, there remains a lack of sufficient information about the ion conductivity and ion transport behaviors of LDHs. In this study, the cation incorporation behavior in CoAl-LDH was investigated with variation in the applied bias in LiCl and LiNO₃ electrolytes. Depending on the applied bias in the electrolyte, the optical properties of the CoAl-LDH changed from its original bluish-green color to a pale-brown or dark-brown color. Chemical investigations verified that the cations and anions constituting the LDH could be expelled or incorporated into the electrolyte depending on the applied bias and electrolyte.