Electrochemical reduction of nitrite at polymeric Co(II)-tetra-3-amino-phenyl-porphyrin modified electrode

This paper describes the electrochemical reduction of nitrite ion in basic media 0.2M KHCO3, with glassy carbon or ITO electrodes modified with a conducting polymer derived from Co(II)tetra-3-aminophenyl-porphyrin. Cyclic voltammetry results show an enhancement in the current of the corresponding Co(II)/Co(I) redox couple when the solution contains 0.02M nitrite. When spectroelectrochemical experiments were performed in the support electrolyte, the modified electrode does not stabilize Co(I) oxidation state, but when there is nitrite in the solution a band at 549nm appears, indicating the stabilization of Co(I) oxidation state probably due to the formation of an intermediary complex between the Co(I) and nitrite. Controlled potential electrolysis experiments verify the production of ammonia and hydrazine even at very negative potentials, showing the electrocatalytic character and the stability of this modified electrode.