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The self assembled monolayer(SAM) of 11 mercaptoundecanoic acid [HS(CH 2) 10 COOH] was formed on a gold electrode and the effect of the charge of end group on the electrochemical response of Fe(CN) 3- 6 at the SAM modified electrode was studied by cyclic voltammetry. At high pH, when the —COOH groups are dissociated, the current of Fe(CN) 3- 6 is suppressed; as the solution pH is lowered, the current of Fe(CN) 3- 6 increases. The electrochemical titration curve was obtained by correlating the currents of Fe(CN) 3- 6 to the different pH values of electrolyte, from which the surface p K a was obtained to be 3.0±0.2. Furthermore, the reason of small p K a value was explained using SAMs of different surface coverage.
The self assembled monolayer (SAM) of 11 mercaptoundecanoic acid [HS (CH 2) 10 COOH] was formed on a gold electrode and the effect of the charge of end group on the electrochemical response of Fe (CN) 3- 6 at the SAM modified electrode was studied by cyclic voltammetry. At high pH, when the-COOH groups are dissociated, the current of Fe (CN) 3-6 is suppressed; as the solution pH is lowered, the current of Fe increases. The electrochemical titration curve was obtained by correlating the currents of Fe (CN) 3- 6 to the different pH values of electrolyte, from which the surface p K a was obtained to 3.0 ± 0.2. K a value was explained using SAMs of different surface coverage.