Polypyrrole films overoxidation

Figure 3.80 Values of n, k and thickness L obtained t ia three parameter fits to the A, T and intensity data obtained during the growth of a polypyrrole film on a sputtered Pt electrode in N2-saturated I M NaCIO4/0,l M pyrrole. The potential was stepped from OV to 0.8 V vs, SCE for 15 s, and readings taken every 20 ms. Reprinted from tkarochimica Acia, 36. P,A. Christensen and A. Hamnett, In situ Spectroscopic Investigations of the Growth, Electrochemical Cycling and Overoxidation of Polypyrrolc in Aqueous Solution, pp. 1263-1286 (1991), with kind permission from Pergamon Press Ltd., Headington Hill Hall. Oxford 0X3 OBW, UK.

Yogeswaran et al., designed a new bimetallic nanoparticles (Au and Pt) modified electrodes for simultaneous determination of AA, EP and UA [169], First, a composite film comprising of functionalized multiwall carbon nanotubes and nafion was formed on the GC electrode. Then Au and Pt NPs were electrochemically deposited on to the composite film modified GC electrode. The voltammetric peaks of AA, EP and UA are well resolved with the peak separations of 222 mV and 131 mV respectively. Lu et al., demonstrated the determination of UA on GC electrode electrodeposited with AuNPs and DNA [170], Clean GC electrode was immersed into a AuNPs colloidal solution and a potential of +1.5 V is applied for 60 min for the deposition of AuNPs. Then the electrode was dipped into a DNA solution (0.1 mg/ml) and a potential of +1.5 V is applied for 30 min to electrodeposit DNA. Finally, DNA/AuNPs modified electrode excellently separates the voltammetric signals of UA, NEP and AA. Li et al., electrodeposited AuNPs on the GC electrode modified with the ultrathin overoxidized polypyrrole film [171], The modified determines the UA in the presence of EP and AA with a lowest detection limit of 1.2 x 10"8 M. 

J. Li and X. Lin, Electrodeposition of gold nanoclusters on overoxidized polypyrrole film modified glassy carbon electrode and its application for the simultaneous determination of epinephrine and uric acid under coexistence of ascorbic acid. Anal. Chim. Acta, 596, 222-230 (2007). 

Ersoz, A., Gavalas, V. G., and Bachas, L. G. (2002). Potentiometric behavior of electrodes based on overoxidized polypyrrole films, AngLBiogngLChem., 372, 786-790. 

Li, Y, Wang, R, Wang, L., and Lin, X. [2007]. Overoxidized polypyrrole film directed single-walled carbon nanotubes immobilization on glassy carbon electrode and its sensing applications. Biosens. Bioelectron., 22, pp. 3120-3125. 

Vidal J.C., E. Garcia, and J.R. Castillo. 1999. In situ preparation of a cholesterol biosensor Entrapment of cholesterol oxidase in an overoxidized polypyrrole film electrodeposited in a flow system Determination of total cholesterol in serum. Anal Chim Acta 385 213. 

A. Witkowski, M. S. Freund, A. Brajter-Toth, Effect of electrode substrate on the morphology and selectivity of overoxidized polypyrrole films, Analytical Chemistry 1991, 63, 622. 

In the latter example and others involving polypyrrole films electroformed from a complex between a transition metal (Ru(II)) and a bi- or terpyridine-substituted pyrrole [201, 202], the electron self-exchange was ensured by either the viologen or Ru(II) units and not by the polymer. As a matter of fact, the PPy matrix was undoped when poly(3) was used for electrocatalytic reduction experiments or overoxidized when the films containing ruthenium(II)-based complexes were involved in oxidation experiments [201, 202]. 

Reference Electrodes Based on Overoxidized Polypyrrole Films... 

Chou group described the conducting polymer reference electrodes (CPRE) based on overoxidized polypyrrole films [36-38]. Polypyrrole films were deposited... 

In a potentiometric process, a wide range of current or charge densities are reported. A typical current density of 0.5 mA/cm, or 30 mC/cm, is a good starting point for exploring optimal plating conditions. It was found that the use of current densities greater than 2 mA/cm resulted in the formation of an overoxidized polypyrrole film with reduced conductivity [79]. 

Gao ZQ, Zi MX, chen BS (1994) the influence of overoxidation treatment on the permeability of polypyrrole film. J Electroanal chem 373 141-148... 

Reverse oxidation and overoxidation (or degradation) processes can be followed as a function of the applied electric potential by voltammetry. A bilayer (3 x I cm) constructed with a 5 mg polypyrrole film was submitted to a potential sweep between - 100 mV (vs. SCE) and 3000 mV in a I M LiC104 aqueous solution. To attain an equilibrium state at every potential (the oxidation state of all the solid correlates with each potential), the sweep rate was slow 3 mV/s. The experimental volt-ammogram is shown in Fig. 36.6. At - 100 mV the poly-... 

Wanekaya A, Sadik OA (2002) Electrochemical detection of lead using overoxidized polypyrrole films. J Electroanal Chem 537 135-143... 

Shiigi, H. Okamura, K. Kijima, D. Deore, B. Sree, U. Nagaoka, T. (2003). An Overoxidized Polypyrrole/Dodecylsulfonate Micelle Composite Film for Amperometric Serotonin Sensing. Journal of The Electrochemical Society, 150, H119-H123. 

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