Electrochemistry of a Thin Cobalt(II)-Heptacyanonitrosylferrate Film Modified Glassy Carbon Electrode

Abstract

During the past years inorganic film modified electrodes have received increased attention due to their potentials in technical applications. Various inorganic materials, such as clays 1 , zeolites 2 , metal oxides 3 , metal phthalocyanines 4 , metal porphyrins 5 , transition metal 6 , polyoxometallates 7 and polynuclear transition metal cyanides [8][9][10] , have been used to fabricate inorganic film modified electrodes. Of these, the use of polynuclear transition metal cyanides as modifiers appears to be especially attractive because a large number of these compounds can be easily prepared. In addition, the well-defined zeolite-like structure makes the description and understanding of the charge-transfer process easier compared with that of organic polymer films. 11Since the pioneering work of Neff and Itaya 8 on Prussian Blue modified electrodes, the field of polynuclear transition metal cyanides modified electrodes has undergone considerable progress over the past years. However, considering the limited diversity of these chemically synthesized compounds, there is still muchwork to be done.In this paper, we report on a method for preparing thin films of CoHNF on glassy carbon electrode surface. The modified electrode exhibits excellent stability in aqueous media. The parameters which affect the voltammetric behavior were examined. Possible analytical applications were attempted. Experimental Materials and apparatusAll chemicals were of certified analytical grade (Merck) and used as received. Solutions were prepared with distilled deionized water from a Millipore system (Millipore, Milford, MA, USA). A 3-mm diameter glassy carbon electrode was polished and cleaned according to a procedure published elsewhere. 10Cyclic voltammetric and electrochemical impedance spectroscopic (EIS) experiments of the modified electrode were carried out as described previously.10 All electrochemical measurements were conducted using a conventional three-electrode system with a triangle arrangement. The modified electrode was used as the working electrode, with a platinum foil counter electrode and a saturated calomel reference electrode (SCE). All potentials reported in this work are referred to the the SCE. ProceduresThe glassy carbon electrode was scanned from -0.6 to -1.15 V in an oxygen-free 1×10 -2 M CoCl 2 -0.1 M KNO 3 solution with a potential scan rate of 20 mV/s and kept at a potential of -1.15 V for a certain period of time. After being removed from the solution and thoroughly rinsed with water, the electrode was dipped in a 0.1 M K 2 [Fe(CN) The electrochemical behavior of a cobalt(II)-heptacyanonitrosylferrate (CoHNF) film on a glassy carbon electrode has been investigated. Cyclic voltammetry shows a single electron-transfer reaction taking place at 0.51 V for the modified electrode. The ion effect of the supporting electrolyte indicates that the ion permeability in the CoHNF film is mainly determined by the hydrated radius of cation. The modified electrode catalyzes redox reactions of the Fe 2+ /Fe 3+ couple. It a...

Preparation and characterization of electrochemical and electrocatalytic behavior of a zinc pentacyanonitrosylferrate film-modified glassy carbon electrode

“…These may be attributed to [Fe II (CN) 5 NO] 2À/3À system as reported previously on the mercury electrode [15]. As pH decreased the anodic peak depressed (curve b), this is in accordance either with formation of [Fe II (CN) 4 NO] 2À by release of HCN [16] or formation of [Fe II (CN) 5 NOH] 2À [17]. Note that unlike the hexacyanoferrate ion any peaks corresponding to Fe III /Fe II redox system is no discernible confirming that the Fe II in NP cannot be oxidized to Fe III .…”

“…These workers also described a method for preparing a thin film of cobalt(II) pentacyanonitrosylferrate on a GC surface [4]. In our laboratory for the first time, aluminum was used as an electrode [5] and the modification of its surface by a thin film of NiPCNF [6][7][8][9] and PdPCNF was reported [10,11].…”

Electrode modification using iron metallophthalocyanine through click chemistry and axial ligation with pyridine

“…This can be attributed to the inert or unreactive electrochemical nature of the grafted diazonium and the clicked pyridine groups, which form an insulating layer on the surface and do not interact with the electrolyte or the analyte -thus slowing the electron transfer kinetics. The surface with FePc, (iv), gave an R CT value of 0.569 kX and showed a depressed semicircle followed by a diffusion-controlled response, which has in some cases been seen both with thin films [48] and with phthalocyanine-modified surfaces [49][50][51]. This decrease in R CT after modifying the electrode with FePc is attributed to the known catalytic properties of the metallophthalocyanines and hence the electron transfer is enhanced [28].…”

Electrochemical characterization of praseodymium centers in Pr x Zr1−x O2 zirconias using electrocatalysis and photoelectrocatalysis

“…In addition, the electrocatalytic reduction of nitrite ions in aqueous solution has received a great deal of interest in respect of developing sensitive and selective methods for its determination [27,28]. Among others, the catalytic effect of transition metal oxides [29], metal complexes [30], redox-active films [31], and Keggin-type and Dawson-type polyoxometalate polymers [32][33][34] and model compounds for nitrite reductase immobilized into polymer films [35] have been studied. Photoelectrochemical reduction of nitrite was searched on the surface of an electrochemically roughened silver electrode [36] and semiconductor photocatalysts CdS [37].…”