Electrochemical behavior of K3Fe(CN)6 in water-in-oil microemulsion

A water-in-oil (W/O) microemulsion composed of Triton X-100, n-hexanol, n-hexane and water solution with hydrochloric acid was prepared. K3Fe(CN)(6) was added in as a water-soluble electroactive probe, and its electrochemical behavior was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that the H+ concentration of the water phase has a great effect on the conductivity of the W/O microemulsion, and hence influences the electrochemical behavior of K3Fe(CN)(6). When the pH value of water phase is about 7, the electrical conductivity of the W/O microemulsion is only 1.2x10(-6) S/cm, and K3Fe(CN)(6) almost cannot react at the glassy carbon electrode. But when the H+ concentration is more than 3 mol/L, the W/O microemulsion has a good electrical conductivity and K3Fe(CN)(6) shows good electrochemical performance in it. The results of CV and EIS studies indicate that the electrochemical behavior of Fe(CN)(6)(3-)/Fe(CN)(6)(4-) in the W/O microemulsion is different from that in the aqueous solution. This may be due to the unique liquid structure of the W/O microemulsion and the unique mass transfer in the W/O microemulsion.