Polypyrrole electrode

Figure47. Chronoamperometric responses to potential steps carried out using a polypyrrole electrode from -2000 to 300 mV vs. SCE for 50 s, in 0.1 M UCI04 solutions of different solvents. (Reprinted from H.-J. Grande, T. F. Otero, and I. Cantero, Conformational relaxation in conducting polymers Effect of the polymer-solvent interactions. 7. Non-Cryst. Sol. 235-237,619, 1998, Figs. 1-3, Copyright 1998. Reproduced with kind permission of Elsevier Science-NL, Sara Burgerhartstraat 25, 1055 KV Amsterdam, The Netherlands.)...

Figure 60. Experimental responses to anodic potential sweeps carried out on a polypyrrole electrode in a 0.1 M UC104-propylene carbonate solution from -2500 to 300 mV, at 30 mV s-1 and different temperatures ranging between -10 and 40°C. Cathodic prepolarization was always performed at 25°C and maintained for 2 min, avoiding any difference in the degree of closure of the polymeric entanglement at the beginning ofthe potential sweep. (Reprinted from T. F. Otero, H.-J. Grande, and J. Rodriguez, J. Phys. Chem. 101, 8525, 1997, Figs. 3-11, 13. Copyright 1997. Reproduced with permission from the American Chemical Society.)...

The catalytic activity of viologen modified polypyrrole electrodes in preparative elK tror luctions has been extended from vicinal to geminal poly-... 

Ingram, M. D., H. Staesche, and K. S. Ryder, Activated polypyrrole electrodes for high-power supercapacitor apphcations. Solid State Ionics, 169, 51 (2004). 

Cyclic voltammetry was performed with the ADH-NAD-MB/polypyrrole electrode in 0.1 M phosphate buffer (pH 8.5) at a scan rate of 5 mV s l. The corresponding substrate of ADH caused the anodic current at +0.35 V vs. Ag/AgCl to increase. These results suggest a possible electron transfer from membrane-bound ADH to the electrode through membrane-bound NAD and MB with the help of the conductive polymer of polypyrrole. 

An electron transfer type of enzyme sensor was thus fabricated by a electrochemical process. Although no appreciable leakage of ADH and MB from the membrane matrix was detected, NAD leaked slightly. To prevent this leakage, the ADH-MB-NAD/polypyrrole electrode was coated with Nation. A calibration curve is presented in Fig.25 for ethanol determination in an aquous solution with the enzyme sensor. Ethanol is selectively and sensitively determined in the concentration range from 0.1 nM to 10 mM. 

In a further development, an ADH-MB-NAD/polypyrrole electrode, a platinum counter electrode and an Ag/AgCl reference electrode were assembled and covered with a gas-permeable polymer membrane to form an gaseous ethanol sensor. This appears to be the first time that a complete enzyme sensor for gaseous ethanol has been fabricated in such a manner with NAD incorporated in immobilized form. 

FIG. 23. Charge discharge curves for nanotubular (a) and thin film (b) LiMn204/ polypyrrole electrodes. Current density = 0.1 mA cm. Electrolyte was 1 M LiC104 in 1 1 (vol.) propylene carbonate dimethoxyethane. 

Fig. 9.12 Cyclic voltammetry of the p-doping(anodic)-undoping(cathodic) process of a polypyrrole electrode in LiClO -PC solution. Pt substrate, Li reference electrode, scan rate 50 mV s .

As expected, the impedance responses obtained in practice do not fully match that of the model of Fig. 9.13. However, as shown by the typical case of Fig. 9.14 which illustrates the response obtained for a 5 mol% ClO -doped polypyrrole electrode in contact with a LiC104-propylene carbonate solution (Panero et al, 1989), the trend is still reasonably close enough to the idealised one to allow (possibly with the help of fitting programmes) the determination of the relevant kinetics parameters, such as the charge transfer resistance, the double-layer capacitance and the diffusion coefficient. 

Fig. 9.14 The ac impedance response of a Q04-doped polypyrrole electrode over a frequency range extending from 0.006 Hz to 6.5 kHz.

Fig. 9.16 Cyclic behaviour of lithium batteries using standard pPy(C104) polypyrrole electrodes and modified pPy(DS) electrodes.

Fig. 9.17 In-situ absorbance spectra of a polypyrrole electrode in contact with a LiClOij-PC electrolyte (1) poorly doped (2) highly doped immediately after charge (3) after 5.5 hours and (4) after 17 hours of storage (5) electrochemically regenerated (from Scrosati (1989)).

The tetraphenylborate ion-doped polypyrrole electrode was sensitive to zinc ions [464, 465], and its sensitivity was dependent on the polymer macrostructure. 

S. Razola Serradilla, B. Ruiz Lopez, N. Diez Mora, H.B. Mark and J.M. Kauffmann, Hydrogen peroxide sensitive amperometric biosensor based on horseradish peroxidase entrapped in a polypyrrole electrode, Biosens. Bioelectron., 17(11-12) (2002) 921-928. 

Nagai H. and Segawa H. (2004), Energy-storable dye-sensitised solar cell with polypyrrole electrode , Chem. Comm., 974-975. 

Koleli et al. studied conducting polymer films as electrode materials for CO2 reduction. " They showed that polyaniline supported by a Pt sheet reduces CO2 to HCOOH, HCHO and CH3COOH in methanol based electrolyte at -0.4 V vs. SCE under ambient to elevated pressures up to 20 kbar. The current density is 1 to 2 mA cur with the total faradaic efficiency of the products close to 100%. They obtained similar results in polypyrrol electrode as well. 

Schrebler et al. used Re or Re-Cu dispersed polypyrrole electrodes supported by Au substrates for CO2 reduction in methanol based electrolyte. The current density was 1 mA cm" or so at -1.35 V vs. SCE. The products were CO and CH4 with good faradaic balances. ... 

Schrehler, R., Cury, P., Suarez, C., Munoz, E., G6mez, H., and Cordova, R., Study of the electrochemical reduction of CO2 on a polypyrrole electrode modified by rhenium and copper-rhenium microalloy in methanol media, J. Electroanal. Chem., 533, 167-175, 2002. 

Y. Ikariyama and W. R. Heineman, Polypyrrole Electrode as a Detector for Electroinactive Anions by Flow Injection Analysis. Anal. Chem., 58 (1986) 1803. 

Carbon dioxide electroreduction can be carried out on modified polypyrrole electrodes [81,82,180]. The active electrodes are obtained by electropolymerizalion of Re(L)(CO)3Cl complex, where L is a pyrrole-substituted ligand of various length. The active species is the immobilized rhenium complex. The main reaction product in acetonitrile is carbon monoxide, and preparative-scale electrolysis gave efficiencies as high as 90%. 

In the light of their exhaustive quartz-crystal micro-gravimetric, potentiometric, UV-VIS, Raman spectro-electrochemical, GC/Mass studies, Chen and Rajeshwar [261] reported an unusual type of instability in the polypyrrole electrode caused by the chemical species generated during electrolysis. It was observed that hypochlorite ions were produced at the cathode involving the electron transfer reaction between OH and Cr in the electrolyte and thus generated hypochlorite ions were found responsible for polypyrrole film dissolution. 

T.F. Otero, S.O. Costa, MJ. Ariza, and M. Marquez, Electrodeposition of Cu on deeply reduced polypyrrole electrodes at very high cathodic potentials, J. Mater. Chem., 15, 1662 (2005). 

V.M. Jovanovic, S. Terzic, and A. Dekanski, Characterization and electrocatalytic application of silver modified polypyrrole electrodes, J. Serb. Chem. Soc., 70, 41-49 (2005). 

Kong, Y, Wei, J., Wang, W, and Chen, Z. (2011). Separation of tryptophan enantiomers with polypyrrole electrode column by potential-induced technique, Electrnchim.Acta. 56,4770-4770. 

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