Porphyrin Nanorods Modified Glassy Carbon Electrode for the Electrocatalysis of Dioxygen, Methanol and Hydrazine

Abstract

Abstract Porphyrin nanorods (PNR) were prepared by ionic self‐assembly of two oppositely charged porphyrin molecules consisting of free base meso ‐tetraphenylsulfonate porphyrin (H 4 TPPS 4 2− ) and meso ‐tetra( N ‐methyl‐4‐pyridyl) porphyrin (MTMePyP 4+ M=Sn, Mn, In, Co). These consist of H 4 TPPS 4 2− SnTMePyP 4+ , H 4 TPPS 4 2− CoTMePyP 4+ , H 4 TPPS 4 2− InTMePyP 4+ and H 4 TPPS 4 2− MnTMePyP 4+ porphyrin nanorods. The absorption spectra and transmission electron microscopic (TEM) images of these structures were obtained. These porphyrin nanostructures were used to modify a glassy carbon electrode for the electrocatalytic reduction of oxygen, and the oxidation of hydrazine and methanol at low pH. The cyclic voltammogram of PNR‐modified GCE in pH 2 buffer solution has five irreversible processes, two distinct reduction processes and three oxidation processes. The porphyrin nanorods modified GCE produce good responses especially towards oxygen reduction at −0.50 V vs. Ag|AgCl (3 M KCl). The process of electrocatalytic oxidation of methanol using PNR‐modified GCE begins at 0.71 V vs. Ag|AgCl (3 M KCl). The electrochemical oxidation of hydrazine began at around 0.36 V on H 4 TPPS 4 2− SnTMePyP 4+ modified GCE. The GCE modified with H 4 TPPS 4 2− CoTMePyP 4+ H 4 TPPS 4 2− InTMePyP 4+ and H 4 TPPS 4 2− MnTMePyP 4+ porphyrin nanorods began oxidizing hydrazine at 0.54 V, 0.59 V and 0.56 V, respectively.