The Spectroelectrochemical Study of the Oxidation of 1,2‐Diaminobenzene: Alone and in the Presence of Ni(II)

Abstract

A rapid scanning spectrometer and classical electrochemical techniques have been combined in a spectroelectrochemical experiment using optically transparent electrodes to study electrode filming on the oxidation of 1,2‐diaminobenzene; alone and in the presence of Ni (II). Spectroelectrochemical studies of short‐lived redox intermediates and mechanisms of the oxidation at platinum electrodes are determined. Cyclic voltammetry showed the oxidation of 1,2‐diaminobenzene to be irreversible, and on successive scans without cleaning the electrode the peak current dropped significantly with each scan until ultimately no current flowed. This situation is indicative of an insulating film completely coating the electrode. This behavior was observed both with and without Ni(II) being present in solution. However, there were significant differences in the rate and nature of the filming. Spectroelectrochemically, it was observed that the nature of the film on 1,2‐diaminobenzene oxidation was independent of time and potential. A conducting film is initially formed, and on top of this a nonconducting film forms which eventually insulates the electrode. With Ni(II) present, the oxidation mechanism is potential dependent. At lower potentials a product containing nickel is formed which does not coat the electrode. At higher potentials the product was found to be the same insulating film which coated the electrode in the oxidation of 1,2‐diaminobenzene without the presence of Ni(II).

Amperometric Biosensor for Glucose Based on a Nanometer-Sized Microband Gold Electrode Coimmobilized with Glucose Oxidase and Poly(o-phenylenediamide)

“…1), which was different from those in literature [20,22,25]. In those reports, two irreversible oxidation peaks at about þ0.35 V and þ0.55 to þ0.6 V had been observed in the first cycle, and then the first peak at þ0.35 V disappeared.…”

“…Our experiments chose an electrolysis time of 5 min for the formation of GOD/poly-PDA film. The charge in current was different from those in [22] and [28], resulting from both the adsorption of GOD on the electrode surface prior to the electropolymerization [27] and the exposition of active dots of electrode surface due to the incorporation of GOD. The former decreased the oxidation rate of PDA and made the formation of an insulating polymer film slower.…”

“…After 3 to 4 cycles the peak disappeared and the wave trended to a background shape, indirectly, but clearly indicating that a compact and insulating film was formed and the film was substantially free from holes [25]. According to Yacynych's explanation, a conducting film was initially formed, and on the top of this a nonconducting film formed which eventually insulated the electrode [22]. Usually, it is difficult to form a film at a microelectrode due to its fast mass transport.…”

“…The reaction mechanism of electropolymerization has been well studied [20][21][22][23]. Due to permselectivity characteristics of the membrane, it can produce a sensor virtually free from the interference of ascorbic acid and its fouling problem [24].…”

Evaluation of Poly(o‐phenylenediamine) Films for Application as Insulating Layers upon Carbon Substrates for Use within Sonochemically Fabricated Microelectrode Arrays

“…Among electrodeposited polymers, the material poly(o-phenylenediamine) (PoPDA) has received a great deal of attention over the last 20 years. Since the first report on the polymerization of o-phenylenediamine (oPD) on conducting substrates via electrochemical oxidation [1], a number of papers have appeared on possible applications of the resultant polymer films. Recently, PoPDA has been utilized as permselective membrane in biosensor design [2], a surface modifying agent to facilitate immunospecies detection [3] and as a component in rechargeable cells [4].…”