Carbon paste electrode chemically modified by direct admixing of tris[4,7-diphenyl-1,10-phenanthroline]iron(II)

Direct incorporation, by admixing, of tris[4,7‐diphenyl‐1,10‐phenanthroline]iron(II) cation and perchlorate as counteranion with carbon paste electrodes resulted in chemically modified surfaces of promising electrochemical behavior. The electrochemical performance of the modified surfaces was characterized by cyclic voltammetry. One reduction peak and one oxidation peak, which were almost pH independent in the 1.00–5.00 pH range, are observed at ca. +1.00 and +1.20 V vs. Ag/AgCl, respectively. The cathodic peak remains constant with successive cycling of the potential, but the less well‐developed anodic peak disappears. The same effect was observed after sustained application (several hours) of a + 1.0 V potential. Perchlorate offers certain advantages as counteranion over salicylate, benzoate, and dodecylbenzenesulfonate. The modified surfaces have a low rate of loss of the complex by leaching and are useful for the catalytic sensing of redox species, particularly gaseous analytes in continuous‐flow systems. The hydrodynamic voltammetric behavior of NO2(g) is presented to illustrate this point.