Electrocatalytic activity of a new nanostructured polymeric tetraruthenated porphyrin film for nitrite detection Original Research Article

The preparation of the monomer and thin films of a new polymeric tetraruthenated porphyrin material and their characterization by spectroscopic and electrochemical techniques, are described. This material is one of the most active electrocatalyst for the oxidation of nitrite ions to nitrate, exhibiting a heterogeneous cross-exchange rate constant (kf=(6.2±0.1×104) M–1 s–1) 30 times higher than that previously described for the electrostatic assembled porphyrin films. The polymeric films were obtained by electropolymerization of the corresponding molecular films, previously prepared by dip-coating. This strategy leads to an increase in the efficiency of the reticulation process while minimizing the amount of monomer necessary for the preparation of the modified electrodes. The conductivity of the thin films close to the E1/2 of the Ru(III/II) redox pair is very good, decreasing rapidly as the applied potential departs from it, as expected for a redox polymer. The conductivity decreases when the surface concentration becomes higher than 1.2×10–8 mol cm−2 also, reflecting a higher impedance for electrolyte diffusion inside the polymeric material. The high electrocatalytic activity associated with the high conductivity make this new nanostructured material suitable for sensor applications.