Electrochemical characteristic of 2-mercaptobenzothiazole self-assembled monolayer on gold

A monolayer membrane of 2-mercaptobenzothiazole (MBT) was prepared on a gold electrode through a self-assembly procedure. The monolayer structure and the electrochemical properties were investigated by various electrochemical techniques, like cyclic voltammetry and an impedance measurement with external redox. Experiments show that MBT can form a closely packed monolayer that can be charged due to the active N atom. The amount of charge on the membrane surface varies with the solution pH, and the monolayer shows 'opening and closing' which depends on the solution pH. The electrostatic interaction of the monolayer with other ions is also related to the pH in solution. An impedance analysis shows that the heterogeneous electron-transfer rate of a fast redox like Fe(CN)₆(3-/4-) decreases from 1.2 x 10^-2 to 4.7 x 10^-5 cm s^-1 in neutral solution due to blockage of the self-assembled monolayer membrane.