Electrooxidation of Nitrite Ions on Gold/Polyaniline/Carbon Paste Electrode

Abstract

Nitrite ions can penetrate from fertilizers into underground water and consequently contaminate the water and food sources. A facile two-step electrochemical method was used to fabricate gold/polyaniline/carbon paste electrode (Au/PAni/CPE) for nitrite sensing. The Au/PAni/CPE was visualized and characterized by scanning electron microscopy, energy-dispersed X-ray spectroscopy, X-ray diffraction and electrochemical methods. The electrocatalytic activity of bare CPE, PAni/CPE and Au/PAni/CPE toward the electrooxidation of nitrite was examined and compared via cyclic voltammetry. To obtain the optimal condition for fabrication of the electrode, the number of cycles in cyclic voltammetry for synthesis of polyaniline and the deposition time in potentiostatic deposition of gold were optimized with respect to the electrooxidation of nitrite. In a phosphate buffer solution (PBS, pH 7.0), the peak current was linear to the concentration of nitrite in the range from 3.8×10−5 M to 1.0×10 −3 M with a detection limit of 2.5×10 −5 M. The interference effect on the nitrite detection was also studied. The proposed method was also employed for the determination of nitrite in rain and lake water samples.

Modelling Reversible Inhibition of Irreversible Electro-Oxidation

“…In the reverse branch of cyclic voltammogram the oxide layer is reduced to metallic platinum and the anodic peak corresponding to methanol oxidation appears again. Similar anomalous cyclic voltammograms that consist of anodic peaks in both anodic and cathodic branches were observed in electro-oxidations of ethanol [12 -16], glycerol [16,17] and formic acid [18]. Apart from pure platinum [1, 6 -8, 11, 14, 16, 18] and its alloys with ruthenium [2,3] and rhodium [13], various catalysts were used, such as palladium [5,10,12], gold [17], Fe2(MoO4)3 [4] and nickel [15].…”

Multiple Pulse Amperometry—An Antifouling Approach for Nitrite Determination Using Carbon Fiber Microelectrodes

“…The nitrite oxidation signal recorded by cyclic voltammetry with a freshly polished electrode decays at each cycle, and the passivation of the surface by oxides produced during nitrite oxidation [ 34 ] or poisoning of the electrode usually explains this response loss [ 22 ]. Figure 1 A shows an example of such a problem, as a continuous anodic current decrease is observed during the potential cycling using a carbon fiber microelectrode.…”

“…Although electrochemical detection via oxidation is usually preferred, the use of bare electrodes is limited by surface poisoning and passivation [ 22 , 23 ]. Some strategies can be employed to overcome these limitations, such as electrode surface modification, pretreatment [ 24 ], and pre-stabilizing the electrode signal before the analysis.…”

Electrocatalytic Oxidation of Ethanol on Flexible Three‐dimensional Interconnected Nickel/Gold Composite Foams in Alkaline Media

“…As seen, upon addition of 1.0 M ethanol, a new peak with higher current density is appeared that can be attributed to the ethanol electro‐oxidation. Meanwhile, the shift in the oxidation potential to negative values compared with LSV (Figure a) could be related to decreased association of residual species produced from the forward scan on the surface of the catalyst . In order to highlight the effect of AuNPs, CV graphs of 3D NiF with and without AuNPs are presented in Figure c.…”