Study on the Properties of an Electrochemical Sensor of Modified Methylene Blue on Vitreous Carbon Electrode

Abstract: This paper discribed the structure and electrochemical properties of MB adsorption layer on the surface of vitreous carbon electrode. The experimental results showed that the molecules of MB were adsorbed on the surface of vitreous carbon in the form of dimer, and it would dissociated to form a monolayer in special conditions, such as treating the modified electrode in ethanol under ultrasonic or in boiling water. We studied the electrochemical kinetics of adsorbed MB and calculated some physical chemistry parameters to evaluate the electron-transfer efficiency and to understand the mechanism of the electrochemical reaction. It makes clear that the electrochemical reaction is not a purely charge transference controlled procedure and also not a typical semi-infinite diffusion controlled one. It is reasonable because that the protons in solution were the participants in the redox reaction of adsorptive MB meanwhile the electron transfer in surficial layer. Furthermore, the modified electrode was used in the cyclic voltammetric experiment as a sensor of ferriporphyrin. It could proportionally respond the concentration of ferriporphyrin in deoxygenated neutral phosphate buffer.