Nafion electrodes

The isomerization of 1-butene to cis- and trans- 2-butene onPd/C/Nafion and Pd-Ru/Nafion electrodes is one of the most remarkable and astonishing electrochemical promotion studies which has appeared in the literature.39,40 Smotkin and coworkers39,40 were investigating the electrocatalytic reduction of 1-butene to butane on high surface area Pd/C and Pd-Ru cathodes deposited on Nafion 117 when, to their great surprise, they observed at slightly negative overpotentials (Fig. 9.31) the massive production of 1-butene isomerization, rather than reduction, products, i.e. cis- and trans-2-butenes. This is extremely important as it shows that electrochemical promotion can be used also to enhance nonredox catalytic reactions such as isomerization processes. 

Figure 9.31. Effect of cell potential on the rates of cis- and trans-2-butene and butane formation upon electrochemical reduction of 1-butene on Pd/C/Nafion electrodes at room temperature.35 Reprinted with permission from the American Chemical Society.

Other reactions of small inorganic molecules are the oxidation of chloride ion at a Nafion electrode impregnated with a ruthenium 0x0 complex and the reduction of nitrogen monoxide to ammonia at a Co phthalocyanine modified electrode... 

Nafion is also used as a suitable matrix for enzyme immobilization. In their study Fortier et reported a one-step preparation of GOx/Nafion film on a Pt electrode. At its optimal performance conditions, the Pt/GOx/Nafion electrode also served as a membrane barrier to oxidizable anionic species. However GOx decreased the ability of the Nafion film to exclude anionic interferents. 

Amperometric Nafion Electrode shows sensitivity of 0.16 mA/ppm at room temperature, response time of 45 s rmd recovery time of 54 s, a long-term stability >27 days... 

Enea O (1987) On the electrocatalytic oxidation of methanol vapors at Au-Nafion electrodes. J Electroanal Chem... 

Ho KC, Hung WT (2001) An amperometric N02 gas sensor based on Pt/Nafion electrode. Sens Actuators B 79 11-18 Ho KC, Liao JY, Yang CC (2005) A kinetic study for electrooxidation of NO gas at a Pt/membrane electrode-apphcation to amperometric NO sensor. Sens Actuators B 108 820-827 Imaya H, Ishiji T, Takahashi K (2005) Detection properties of electrochemical acidic gas sensors using halide-halate electrolytic solutions. Sens Actuators B 108 803-807 Ives DJG, Janz GJ (eds) (1961) Reference electrodes theory and practice. Academic, New York, NY Jordan LR, Hauser PC, Dawson GA (1997) Humidity and temperature effects on the response to ethylene of an amperometric sensor utilizing a gold-Nafion electrode. Electroanalysis 9 1159-1162 Katayama-Aramata A, Nakajima H, Fujikawa K, Kita H (1983) Metal electrodes bonded on sohd polymer electrolyte membranes (SPE)—the behaviour of platinum bonded on SPE for hydrogen and oxygen electrode processes. Electrochim Acta 28 777-780... 

The polarization resistance of Pt-Nafion electrode. Electrochim Acta 29 1721-1724 Kita H, Nakajima H (1986) Metal electrodes bonded on solid polymer electrolyte membranes (SPE)-III. CO oxidation at Au-SPE electrodes. Electrochim Acta 31 193-200... 

Lin R, Shih S. Kinetic analysis of the hydrogen oxidation reaction on Pt-black/Nafion electrode. J SohdState Electrochem 2006 10(4) 243-9. 

The kinetic current for oxygen reduction is calculated for Pt-Nafion electrodes in the presence of impurity cations. Figure 1 shows the time course of the ratios of the ORR kinetic current for the contaminated condition with reference to the pure condition, with several levels of Na", Ca ", Fe % and Ni impurity ions. 

Fig. 5 ORR polarization curves of a Pt-Nafion electrode in the presence of 10% Ca without eind with fumaric acid. Scan rate 0.01 V s ...

Fig. 5 (a) Pb(II) adsorption isotherms on porous C03O4 (red line) and layered C03O4 (black line) microsheets. (b-c) SWASV responses of Pb(II) and the corresponding calibration plots on porous Co304/nafion and layered Co304/ nafion electrode at different concentrations in 0.1 M NaAc-HAc solution (pH 5.0). (d) Schematics of how adsorptive nanomaterial could be designed for an electrochemical sensing interface. Reprinted with permission from ref. 51. 

Figure 17 Spectra recorded at-0.90 V vs SCE during the 2nd, 4th, 6th, 8th and 10th cyclic voltammograms for an ITO/Nafion electrode in 0.1 mM 1,1 -dimethyl-4,4 -bipyridilium dichloride +0.2 M KCI (pH 5.5). The vertical arrows indicate absorbance increase with scan number. For a comparable experiment in the absence of Nafion, the maximum absorbance was <0.01. Reproduced with permission from Mortimer RJ and Dillingham JL (1997) Journal of the Electrochemical Soc/efy 144 1549-1553.

Lee GJ, Kim CK, Lee MK, Rhee CK (2010) Advanced Use of Nanobismuth/Nafion electrode for trace analyses of zinc, cadmiirm, and lead. J Electrochem Soc 157 J241-J244... 

One typical example of an electrochemical gas sensor is a NO2 sensor developed by Do and Chang. " PANI was coated on Au/Nafion to form a conjugated polymer/metal/Nafion working electrode. The porous stmcture of coated PANI on the Au/Nafion electrode increases the electroactive area and activity of the sensor. Consequently, an increase in the sensitivity of the NO2 gas sensor was expected when Au/Nafion was replaced with PANI/Au/Nafion as the working electrode. An increase in the concentration of NO2 (in the range 0-100 ppm) resulted in a linear inaease in the current flow of the sensor. The sensitivity of the sensor, which is the slope of the current versus NO2 concentration curve, increased upon exposure to higher gas flow rates as shown in Figure 9. 

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