Electrochemical coating of [trans-L14CoIIICNFeII(CN)5]Na on ITO/Au electrode and its electrocatalytic properties towards nitrite reduction

Abstract The preparation of an ITO (Indium Tin Oxide) modified electrode with a mixed valence Co III /Fe II complex is described. The ITO electrode was initially modified with Au nanoparticles by dip coating in order to obtain and ITO/Au surface over which a film of the [ trans- L 14 Co III NCFe II (CN) 5 ]Na (L 14 Co III –Fe II ; L 14  = 6-methyl-1,4,8,11-tetraazacyclotetradecan-6-amine) complex was deposited electrochemically, thus obtaining an ITO/Au/L 14 Co III –Fe II modified electrode. The modified electrode has been characterized by cyclic voltammetry, Raman spectroscopy, AFM and SEM, thus confirming the presence of the mixed valence complex as a modifier species. The electrode prepared shows good stability in aqueous solution and its activity as electrocatalyst in the reduction of nitrites has been evaluated. Cyclic voltammetry experiments run in presence of nitrites show a current enhancement on the ITO/Au/L 14 Co III –Fe II modified electrodes with respect to the ITO/Au initial electrode. After controlled potential electrolysis experiments, analysis of the products indicate the presence of hydroxylamine as the main nitrite reduction species, although small quantities of hydrazine and ammonia where also obtained.