Surface Effect on Fe (III)Poly-(Tetraaminophenyl) Porphyrin Modified Electrodes After Electrocatalytic Reactions. An Electrochemical and Atomic Force Microscopy Study

• Published in: International journal of electrochemical science Vol. 6; no. 10; pp. 4984 - 4998
• Main Authors: Goya, M.C., Lucero, M., Orive, A. González, Marín, A., Gimeno, Y., Creus, A. Hernández, Aguirre, M.J., Arévalo, M.C., Armijo, F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2011
• Subjects: AFM; Electrocatalytic process; Electropolymerization; Modified electrode; Porphyrin; AFM; Electrocatalytic process; Porphyrin; Modified electrode; Electropolymerization
• ISSN: 1452-3981; 1452-3981
• DOI: 10.1016/S1452-3981(23)18382-9

In this work, Fe(III)-poly-m-TAPP and Fe(III)-poly-p-TAPP films were deposited by electropolymerization on different surfaces, e.g. Au(111), Highly Oriented Pyrolytic Graphite (HOPG), glassy carbon and graphite were studied. Atomic force microscopy (AFM) was utilized to monitor the surface generated on the different substrates before and after performing electrochemical reactions at the modified assemblies. To this purpose two electrochemical reactions were studied, namely the electrooxidation of nitrite and electroreduction of oxygen in order to determine porphyrin structural differences and the effect on film morphology when the modified electrode was used as electrocatalyst in redox processes. First, the electropolymerization mechanism depends on the position of the amino group in the porphyrin backbone. The amino group in para position generates a greater amount of oligomers upon the electrode surface, as evidenced by AFM images obtained at HOPG and Au(111). In general all modified electrodes showed electrocatalytic activity toward O2 electroreduction and NO2- electrooxidation. Fe (III)-poly-p-TAPP modified electrode is better electrocatalysts than Fe (III)-poly-m-TAPP for both reactions in acid and neutral media, respectively. Second, AFM images illustrated how film morphology was affected after being used as electrocatalyst. Fe (III)-poly-m-TAPP film is affected to a greater extent and usually forms aggregates on the electrode surface whereas Fe (III)-poly-p-TAPP films exhibited agglomerates and smooth morphology, but in general its deterioration is more homogeneous. Finally, this study showed how both porphyrin polymer films maintain their electrocatalytic properties after successive voltammetric cycles, demonstrating in some degree their stability.