Electrocatalytic Properties of Ni(II) Schiff Base Complex Polymer Films

Platinum electrodes were modified with polymers of the (±)-trans-N,N'-bis(salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn)]) and (±)-trans-N,N'-bis(3,3'-tert-Bu-salicylidene)-1,2-cyclohexanediaminenickel(II) ([Ni(salcn(Bu))]) complexes to study their electrocatalytic and electroanalytical properties. Poly[Ni(salcn)] and poly[Ni(salcn(Bu))]) modified electrodes catalyze the oxidation of catechol, aspartic acid and NO₂^-. In the case of poly[Ni(salcn)] modified electrodes, the electrocatalysis process depends on the electroactive surface coverage. The films with low electroactive surface coverage are only a barrier in the path of the reducer to the electrode surface. The films with more electroactive surface coverage ensure both electrocatalysis inside the film and oxidation of the reducer directly on the electrode surface. In the films with the most electroactive surface coverage, electrocatalysis occurs only at the polymer-solution interface. The analysis was based on cyclic voltammetry, EQCM (electrochemical quartz crystal microbalance) and rotating disc electrode method.