Nafion SPE Electrodes

From this result, the lai er methanol oxidation current of the Nafion SPE electrode seems to be attributed to this resistance against the contamination rather than the intrinsic activity for the methanol oxidation. 

Platinum chemically deposited on a Nafion membrane was used as a platinum SPE (Solid Polymer Electrolyte) electrode. The electrochemical measurements were performed using the half cell shown in Fig. 2-2. The cell body is made from Teflon (PTFE). The cell is divided into two compartments one for backside gas supply one for the electrolyte. SPE electrodes are placed between them with the deposited side facing the gas compartment. A gold foil with a hole was placed behind the SPE electrode... 

Liu and Fedkiw proposed another SPE electrode formation method, in which cationic salt of platinum instead of chloroplatinic acid, which is used by Takenaka and Torikai, was first impregnated in Nafion and was later reduced chemically. a They showed that product distribution varies depending on the way of the deposition and oxidation conditions. ... 

Fig. 3-39 Methanol oxidation current during potential holding after cleaning steps on platinum Nafion SPE and chemically platinized Pt electrodes. 

Fig. S-40 Hydrogen adsorption-desorption features of Nafion SPE Pt and platinized Pt electrodes b ore and after 24 hour potential holding at GOOmV.

Fig. 3-41 Temperature dependance of methanol oxidation current denai after 2 min. potential holding at 500 mV for Nafion SPE platinum electrode at various methanol concentration in the electrolyte or in the feed gas. 

Fig. 3-43 Methanol oxidation current of Nafion SPE Ft electrode after 2 min. holding at 600mV. Afethanol (p=114mmHg) and water (0 — 152mniHg) were supplied though gas phase. Electrolyte 14 M HsK)4 at 70 C and 130 C. 

Sammclls et al. prepared a Cu coated SPE electrode using a CEM Nafion 11 . They reduced CO2 to C2H4 and C l 1 with the current density of 10 to 30 mA cnf with the terminal voltage 1.5 to 3.5 V. The faradaic efficiency for CO2 reduction remained less than 10%. 

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... 

Fedkiw P, Her W. An impregnation reduction method to prepare electrodes on Nafion SPE. J Electrochem Soc 1989 136 899-900. 

Solid Polymer E,kctroljte. The electrolyte in soHd polymer electrolyte (SPE) units is Nafion, a soHd polymer developed by Du Pont, which has sulfonic acid groups attached to the polymer backbone. Electrodes are deposited on each side of the polymer sheet. H" ions produced at the anode move across the polymer to the cathode, and produce hydrogen. The OH ions at the anode produce oxygen. These units have relatively low internal resistances and can operate at higher temperatures than conventional alkaline electrolysis units. SPE units are now offered commercially. 

The SPE HDH reactor is flexible in terms of structural materials and functions, e.g. electrode materials could be mesh- or carbon-supported gas diffusion ones the SPE could be a cation or anion exchange membrane (e.g. Nafion 117 or Fu-MATech FT-FKE-S) and the reactor can treat either aqueous or non-aqueous (e.g. a paraffin oil) wastes with or without supporting electrolytes. 

Among the exotic cells for the laboratory, flow cells (filter press cells) require an external loop with a pump to recirculate the electrolyte. Also, solid polymer electrode (SPE) cells have been described.16-19 The electrode material is deposited on both sides of a membrane (Nafion) or pressed against the membrane. An advantage is that the ionic conduction takes place in the membrane so that no supporting electrolyte is required. Moreover, this cell can work with gaseous reactants. 

The concept of using an ion-exchange membrane as an electrolyte in electrochemical cells was first introduced by Grubb in 1959. Since then, extensive research and development programs have been undertaken by the General Electric Company and others,resulting in the present solid polymer electrolyte (SPE) cells in which Nafion serves as the sole electrolyte as well as separator. High voltaic efficiency can be achieved in SPE cells because of the minimum contact resistance between electrode and separator. 

Garcia et al. [98] conducted coulometric initiation of acrylamide polymerization in oil-continuous AOT-toluene-water microemulsions using platinum/Nafion solid polymer electrodes (SPEs). The SPE served to separate the microemulsion from an aqueous electrolyte phase. Polymerization was initiated at room temperature by constant-potential electrolytic reduction of potassium persulfate initiator solubilized in the microemulsion droplets. Acrylamide monomer behaved as a cosurfactant and was required for the redox process. Latex particles and solid polyacrylamide were obtained. The kinetics of electroinitiated polymerization was slower than observed with UV or thermal initiation. Latex stability results suggest that coalescence is the primary mechanism for particle growth. 

In the 1960s, the use of solid-state polymer electrolytes instead of the liquid electrolytes normally used in alkaline electrolysis led to the development of novel concepts for water electrolysis. The US company General Electric was the first to realize solid polymer electrolyte water electrolysis (SPE) with the aid of the solid polymer electrolyte membrane (Nafion ) developed by DuPont [16]. At the same time, ABB [17, 18] in Switzerland and Fuji Electric [19] in Japan also developed PEM electrolyzers with single electrode areas of up to 2500 cm. These... 

In all cases, SPE technology involves Nafion membranes and there exist two different ways for obtaining a structurally stable, membrane-electrode assembly. 

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... 

Inappropriate matching of the physicochemical properties of the binder with the carbon material may influence dramatically upon the electroactive area via blocking of the SPE film or simply decreasing the electroactive surface area. Another point to be considered is the cost of the binders. For example, fluoropolymers such Nafion, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) are commonly used as binder in electrode preparation in the field of lithium-ion batteries or fuel cells. However, the curing process has to be soft in most cases... 

Impedance analysis has shown that the large microporosity of carbon could produce an additional proton and/or electronic resistance in the electrode of the capacitors. As a consequence, the specific capacitance did not reach a plateau even at a very low frequency. A difference of about 20% in capacitance for all the supercapacitors was observed between the impedance and DC charge measurements. This was explained in terms of the low electrochemical accessibility of the pores. Later, the same group reported on the effect of polymer electrolyte loading in the electrodes on the performance of the supercapacitor. It reported that the electrodes of the supercapacitor containing 10-30 wt% of Nafion exhibited a higher spe-... 

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