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Sensors 2006, 6(8), 874-891; doi:10.3390/s6080874
Article

Anodic Oxidation and Amperometric Sensing of Hydrazine at a Glassy Carbon Electrode Modified with Cobalt (II) Phthalocyanine–cobalt (II) Tetraphenylporphyrin (CoPc- (CoTPP)4) Supramolecular Complex

Received: 11 April 2006; Accepted: 8 June 2006 / Published: 24 August 2006
(This article belongs to the Special Issue Supramolecular Sensors)
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Abstract: This paper describes the electrocatalytic behaviour of a glassy carbon electrode (GCE)modified with cobalt(II)phthalocyanine (CoPc) complex peripherally tetrasubstituted withcobalt(II)tetraphenylporphyrin (CoTPP) complexes via ether linkages (i.e., CoPc-(CoTPP)4). Thefeatures of the immobilised pentamer were interrogated with cyclic voltammetry andelectrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3-/4- as redox probe revealedenhanced electron transfer properties with kapp ≈ 18 x 10-6 cms-1 compared to that of the bareGCE (4.7 x 10-6 cms-1). The viability of this supramolecular complex as a redox mediator for theanodic oxidation and sensitive amperometric determination of hydrazine in alkaline conditions isdescribed. The electrocatalytic oxidation of hydrazine by GCE-CoPc-(CoTPP)4 was characterisedwith satisfactory catalytic current response with low non-Faradaic current (ca. 30 times lowerthan the bare GCE) and at much lower oxidation potential (ca. 300 mV lower than the bareGCE). A mechanism for the studied electrocatalytic reaction was proposed based on thespectrophotometric evidence that revealed the major involvement of the Co(III)/Co(II) redox coupleof the central CoPc species rather than the CoTPP component of the pentamer. Rate constant forthe anodic oxidation of hydrazine was estimated from chronoamperometry as ~ 3x103 M-1s-1. Theproposed amperometric sensor displayed excellent charateristics towards the determination ofhydrazine in 0.2 M NaOH ; such as low overpotentials ( 100 mV vs Ag|AgCl), very fastamperometric response time (1 s), linear concentration range of up to 230 μM, with micromolardetection limit, high sensitivity and stability.
Keywords: Cobalt(II)phthalocyanine-cobalt(II)tetraphenylporphyrin pentamer ; Electrochemical Cobalt(II)phthalocyanine-cobalt(II)tetraphenylporphyrin pentamer; Electrochemical
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Ozoemena, K.I. Anodic Oxidation and Amperometric Sensing of Hydrazine at a Glassy Carbon Electrode Modified with Cobalt (II) Phthalocyanine–cobalt (II) Tetraphenylporphyrin (CoPc- (CoTPP)4) Supramolecular Complex. Sensors 2006, 6, 874-891.

AMA Style

Ozoemena KI. Anodic Oxidation and Amperometric Sensing of Hydrazine at a Glassy Carbon Electrode Modified with Cobalt (II) Phthalocyanine–cobalt (II) Tetraphenylporphyrin (CoPc- (CoTPP)4) Supramolecular Complex. Sensors. 2006; 6(8):874-891.

Chicago/Turabian Style

Ozoemena, Kenneth I. 2006. "Anodic Oxidation and Amperometric Sensing of Hydrazine at a Glassy Carbon Electrode Modified with Cobalt (II) Phthalocyanine–cobalt (II) Tetraphenylporphyrin (CoPc- (CoTPP)4) Supramolecular Complex." Sensors 6, no. 8: 874-891.


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