Nafion solution

The catalyst inks were prepared by dispersing the catalyst nanoparticles into an appropriate amoimt of Millipore water and 5wt% Nafion solution. Then, both the anode and cathode catalyst inks were directly painted using a direct painting technique onto either side of a Nafion 117 membrane. A carbon cloth diffusion layer was placed on to top of both the anode and cathode catalyst layers [3-5]. The active cell area was 2.25cm. ... 

The slurries of electro-catalysts were prepared by mixing together the catalysts and appropriate amount of 5wt % Nafion solution(Du Pont) including some kinds of dispersant[8]. The electrodes were made by spraying method with these well mixed inks. Two electrodes and Nafion 112 membrane were hot pressed with the condition of 50kgf/cm, 120°C for 3min to fabricate MEAs(Membrane Electrode Assembly). 

The calcined Au/C and AuPt/C powders were mixed with Nafion solution (0.25 wt.%), and were quantitatively transferred to the surface of the polished glassy carbon (GC) disk electrode. 

Brush 5 wt% Nafion solution onto the catalyst layer of this electrode. 

A well-distributed deposition of Pt/C nanocatalyst and Nafion ionomer on bofh hydrophilic and hydrophobic carbon-based electrodes has been successfully obfained using a Pt/C concentration of 1.0 g/L, an electrical field of 300 V/cm, and a deposition time of 5 minutes [118]. The deposition of Pt/C nanocatalysts and Nafion solution via the electrophoretic process gives rise to higher deposition efficiency and a uniform distribution of catalyst and Nafion ionomer on the PEMFC electrodes. 

With increasing water content, the ionic domains swell from 40 to 50 A in diameter and the structure of fhe membrane is fhoughf to consist of spherical ionic domains joined by cylinders of wafer dispersed in fhe polymer matrix. Within this region of wafer confenf, proton conductivify steadily increases. At > 0.5, a morphological inversion occurs in which a connected network of aggregated polymer "rods" is now surrounded by water. This network continues to swell for X, = 0.5 —> 0.9 and fhe conductivify of fhe membrane approaches the values observed for Nafion solutions. 

In the early 1980s, reports surfaced that detailed procedures for dissolving Nafion membranes in water/ alcohol mixtures at elevated temperatures and pres-sures. Currently, Nafion solutions are available commercially, and these solutions are now used in... 

In relatively dilute solutions, Nafion is said to exist in the form of rodlike aggregates of practically the same size - that are in equilibrium with loose ionomers such that at higher concentrations the aggregates dominate. The reader should consult the more recent papers of Gebel et al., cited earlier, for a more detailed view of Nafion solutions . 

The rheological properties change behavior, relative to more dilute solutions, above cp = 0.2, where non-Newtonian behavior is then exhibited. The power law dependence of rj on cp is in harmony with the Zimm rather than the Rouse model, which suggests that hydrodynamic interactions between these polymers, in a mean field sense, are important. Electrical properties also begin to deviate for Nafion solutions above cp = 0.2, and mechanical percolation is essentially the same for the sodium and acid forms. 

Film Fabrication. The platinum electrode (0.28 cm area) was fabricated and cleaned as previously described (19). Thin films of AQ-enzyme were prepared by dissolving an amount of the enzyme, as indicated below, in 10 il of 1.5% AQ polymers solution at room temperature. Two aliquots of 5 il were deposited atop the platinum electrode and the first aliquot was allowed to dry before the second addition. This procedure corresponds to the first protocol. In addition, for the second protocol, 10 il of the 0.5% Nafion solution was casted atop the dried AQ-enzyme film and the methanol was allowed to evaporate at room temperature. The third protocol consisted in the deposition of 10 il of a 1% of AQ solution containing the enzyme, atop the platinum electrode followed by heating in an oven at 50°C during 30 min. In each case, 2 U of glucose oxidase were used. 

To increase the accessibility of the sites, Nafion was encapsulated in a highly porous silica network by use of a sol-gel process [9,10]. Starting from a Nafion solution and soluble silicon sources, a 13 % (w/w) Nafion porous composite was prepared with a 344 m g BET surface area, a 0.85 cm g pore volume, a... 

Polymers (light emitting and conductive) Organome tallies Cyanoacrylates Fuel cell related materials Noble metals (Pt, Pd) for electrocatalysts Nafion solutions Metal nanoparticles (Ag, Au, Cu)... 

FIGURE 15.10 Photograjtis of vials containing 0.5 mg mL of SWCNT (a) and MWCNT (b)in different solutions phosphate buffer (0.05M, pH 7.4) (i), 98% ethanol (ii), 10% ethanol in phosphate buffer (iii), 0.1% Nafion in phosphate buffer (iv), 0.5% Nafion in phosphate buffer (v), and 5% Nahon in ethanol (vi). Also shown (c) is a TEM image of a 0.5% Nafion solution containing 0.3 mg mL of MWCNT. (Reprinted with permission from [64]. Copyright (2003) American Chemical Society.)... 

Bilirubin and bilirubin oxidase were used for cathodic oxygen reduction, while Ru(bpy)3 " /Ru(bpy)3 [Ru(bpy)3 + and Ru(bpy)3 are complex tris (bipyridine)ruthenium(III) and tris(bipyridine)ruthenium(II) cations] was the mediator redox system. In the electrodes, these enzymes were immobilized with Nafion solution treated with quaternary ammonium salts, and put on a support of carbonized cloth, serving as the current collector. The treated Nafion solution helped to maintain enzyme activity for a long time. 

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