Optimizing the Electrocatalytic Activity of Surface Confined Co Macrocyclics for the Electrooxidation of Thiocyanate at pH4

We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH4 exhibit linear amperometric response for thiocyanate concentration in the range 10^-7 and 10^-3M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation.