On the development and application of an in-house fabricated Mg²⁺ ion selective microelectrode (ISME) for assessing mg corrosion

A solid-contact Mg²⁺ ion-selective microelectrode (ISME) usually consists of a carbon fiber coated with conducting polymer, such as electropolymerized 3, 4 ethylenedioxythiopene (PEDOT), in contact with the ion-selective membrane. PEDOT is typically electrochemically deposited onto the carbon fibers from rather expensive ionic liquid based dopants. Herein, Mg²⁺ ISMEs were assembled using a commercially available Mg²⁺ ionophore-containing solution and PEDOT electrochemically deposited from sodium p-toluenesulfonate, thus providing a simple and inexpensive method to develop Mg²⁺ ISMEs. The ISME fabricated by this procedure is successfully able to respond to Mg²⁺ ion concentrations arising from pure Mg during free corrosion and also galvanic corrosion (when Mg is coupled to pure iron).