Ceramic Carbon Electrode Modified with Butyloferrocene

Abstract

Ceramic carbon electrode modified with butyloferrocene was prepared and studied. The electrode consists of graphite powder, homogeneously dispersed in hydrophobic silica matrix. The latter was obtained from organically modified silicate ± methyltrimethoxysilane by sol-gel process. After gelation and drying it was filled with redox liquid ± butyloferrocene by immersion. The properties of the electrode were investigated by cyclic voltammetry and chronoamperometry in aqueous salt solution of different concentration. The cyclic polarization of the electrode in aqueous electrolyte results in peak shaped voltammogram, stable during continuous potential cycling. The modification of the electrode with butyloferrocene diluted by hydrophobic non-electroactive solvent like hexadecane leads to a decrease of the current. The specific voltammogram features were attributed to the redox process of butyloferrocene. The magnitude of the current is proportional to the aqueous electrolyte concentration. It has been concluded that the electrooxidation of redox liquid within hydrophobic silicate matrix is followed by anion transfer from aqueous phase. The electrode process occurs at the three phase junction formed by graphite particles and liquid organic-aqueous interface supported by hydrophobic silicate.

Electroactive Ceramic Carbon Electrode Modified with Hydrophobic Polar Solvent

“…For more diluted tBuFc solution in organic phase smaller number of tBuFc cations is expelled to the aqueous phase and the contribution of Reaction 3 is more significant. In more concentrated electrolyte also more tBuFc cations remains in the organic phase because of a larger supply of NO ) [31] supports this conclusion. In ideal case in the absence of kinetic constraint for ion transfer across liquid j liquid interface any deviation of Q a /Q c from unity should be caused by Reaction 4.…”

“…8) and this effect is proportional to c tBuFc(org) and becomes larger for more concentrated tBuFc. However this effect is significantly smaller than for CCE modified with pure tBuFc where anodic peak current was not well developed and was followed by a sharp current increase at more positive potentials [31]. Interestingly, no significant effect of c AX(aq) on DE 1/2 is observed.…”

“…The absence of current increase in the studied system is probably connected with better solubility of tBuFc in the electrode phase. The peak currents are also better defined than these obtained for CCE modified with concentrated tBuFc solution in hexadecane [30,31]. Interestingly the CV response of the studied electrode is sensitive to the concentration of salt present in aqueous phase contrary to the systems based on nonpolar solvents [28,31].…”

“…The peak currents are also better defined than these obtained for CCE modified with concentrated tBuFc solution in hexadecane [30,31]. Interestingly the CV response of the studied electrode is sensitive to the concentration of salt present in aqueous phase contrary to the systems based on nonpolar solvents [28,31]. Also the dilution with the polar solvent allows one to use a smaller amount of the redox active substance [29,31].…”

“…Also the sensitivity of the electrode to the ion concentration in aqueous electrolyte is smaller. However, in most cases both anodic and cathodic peaks on CV curves obtained with CCE modified with tBuFc solution in NB are better defined in comparison to the wave like shape followed by the sharp anodic current increase [29,31] observed for pure tBuFc modified CCE. The absence of current increase in the studied system is probably connected with better solubility of tBuFc in the electrode phase.…”