Proton electrolyte

Miyake, N., Wainright, J. S. and Savinell, R. E 2001. Evaluation of a sol-gel derived Nafion/silica hybrid membrane for proton electrolyte membrane fuel cell applications. I. Proton conductivity and water content. Journal of the Electrochemical Society 148 A898-A904. 

Due to their high electrical and thermal conductivity, materials made out of metal have been considered for fuel cells, especially for components such as current collectors, flow field bipolar plates, and diffusion layers. Only a very small amount of work has been presented on the use of metal materials as diffusion layers in PEM and DLFCs because most of the research has been focused on using metal plates as bipolar plates [24] and current collectors. The diffusion layers have to be thin and porous and have high thermal and electrical conductivity. They also have to be strong enough to be able to support the catalyst layers and the membrane. In addition, the fibers of these metal materials cannot puncture the thin proton electrolyte membrane. Thus, any possible metal materials to be considered for use as DLs must have an advantage over other conventional materials. 

Methanol is a convenient liquid fuel that can be either blended with petrol or burnt directly in an engine. Utilization of methanol can be envisaged for automotive transport, should a cheap, reliable, long-lived methanol-air fuel cell be developed. Two principal materials problems must be overcome before such a cell can be realized in the market place a proton electrolyte capable of cheap manufacture and stable to about 570 K and a catalytic anode for the conversion of methanol and water via the reaction... 

See color insert following page 140.) A single cell of my reversible fuel cell (RFC) design, using the basic proton electrolyte membrane (PEM) type fuel cell. 

In the proton-emitting membrane or proton electrolyte membrane (PEM) design, the membrane electrode assembly consists of the anode and cathode, which are provided with a very thin layer of catalyst, bonded to either side of the proton exchange membrane. With the help of the catalyst, the H2 at the anode splits into a proton and an electron, while Oz enters at the cathode. On the inside of the porous anode is a thin platinum catalyst layer. When H2 reaches this layer, it separates into protons (H2 ions) and electrons. One of the reasons why the cost of fuel cells is still high is because the cost of the platinum catalyst is rising. One ounce of platinum cost 361 in 1999 and increased to 1,521 in 2007. 

Fig. 4.43 A protonic electrolyte used for measuring the hydrogen content of molten aluminium (adapted from TYK Corporation (Japan) literature see [23]).

At present, a great deal of research is being devoted to the development of intermediate-temperature protonic ceramic fuel cells (IT-PCFCs), which can simultaneously produce value-added chemicals and electrical power [93, 94]. As shown schematically in Figure 12.19, proton conduction implies that water vapor is produced at the cathode, where it is swept away by air (in contrast to the SOFC, where it dilutes the fuel). Consequently, with a purely protonic electrolyte and... 

Composites enable the mechanical and electrical properties of the membrane to be separated. In most cases, they consist of a matrix (mechanical support) filled with a protonic electrolyte. Varying the electrolyte and optimizing the structure of its mechanical support enable the working conditions of the cell to be adapted. This implies an improvement in the performance of the cell, along with a possible reduction in the cost of the membrane. Successful efforts have been made by some groups in this direction. S. Haufe and U. Stimming prepared and characterized composite membranes made by... 

YA. Gallego, a. Mendes, LM. Madeira, S.P. Nunes, Proton electrolyte membrane properties and direct methanol fuel-cell performance I. Characterization of hybrid sulfonated poly-(ether ether ketone)/zirconium oxide membranes. Journal [Pg.85]

The most cited reference electrode is the platinum-hydrogen electrode, and electrode DC potentials are often given relative to such an electrode. It is an important electrode for absolute calibration, even if it is impractical in many applications. The platinum electrode metal is submerged in a protonic electrolyte solution, and the surface is saturated with continuously supplied hydrogen gas. The reaction at the platinum surface is a hydrogen redox reaction H2 2H (aq) + 2e, of course with no direct chemical participation of the noble metal. Remember that the standard electrode potential is under the condition pH = 0 and hydrogen ion activity 1 mol/L at the reference electrode. Thus the values found in tables must be recalculated for other concentrations. Because of the reaction it is a hydrogen electrode, but it is also a platinum electrode because platinum is the electron source or sink, and perhaps a catalyst for the reaction. 

A solid protonic electrolyte battery presents the general advantages of all solid-state systems such as absence of liquid leakage and ease of handling. It must have two electrodes to react with the protons, as in aqueous liquid electrolyte batteries. The main aim for using solid protonic conductors resides in the possibility of using similar electrodes to those in current commercial batteries. 

In an ECD, the electrolyte is used as the reservoir of cations needed for injection into the electrochromic films for either coloration or bleaching. Such a device needs fast response, chemical and electrochemical stability, reversibility and memory properties. To achieve fast coloration kinetics with WO3, the use of protonic electrolytes is very attractive since protons have the highest mobility in the electrochromic films compared with other cations. Their use would then lead to the fastest ECD performances. However, the presence of protons is not sufficient and a conductivity of... 

Most of the earlier studies on proton insertion in ECDs, have been devoted to acidic aqueous electrolytes. However, since most of the electrochromic materials are chemically unstable in acidic medium, commercially viable ECDs must use other electrolytes. Recently, the use of solid anhydrous proton electrolytes seems to be very promising. We present some of the materials which have been used in ECDs. 

Table 38.2. Conductivity of some protonic electrolytes for ECDs...

An alternative approach to conductivity enhancement by crystallinity supression is by the incorporation of inert fillers such as ceramic composites [77]. Another class of materials in which both polymer and organic materials are present are the so-called Ormocers [78] or Ormolytes [79]. These are produced by a sol-gel process in which amino-alkylsilanes are hydrolysed and condensed, and triflic acid (for proton electrolytes) or lithium perchlorate complexed with ethylene glycol diglycidyl ether (for a Li electrolyte) is incorporated. 

Jones D J and Rozibre J (2009), Ambient temperatnre proton electrolyte membrane fuel cells current trends in Encyclopedia of Electrochemical Power Sources, Vol. 2 (C. D. J. Garche, P. Moseley, B. Scrosati, Z. Ogumi, D. Rand, ed.), Amsterdam, Elsevier. 

Yandrasits M (2011), Advances in New Materials for Proton Electrolyte Fuel Cell Systems, CA, Asilomar. 

Hydroxylation of benzene to phenol was implemented at room temperature by applying H -Oj fuel cells that continuously accumulated HjO at room temperature by using an Au cathode attached to a Nafion-H membrane as a protonic electrolyte [146b]. When an iron salt and benzene were loaded into the aqueous solution of HCl in the cathode compartment, phenol was formed due to generation of Fenton reagent. 

Silva VS, Ruffmann B, Silva H, Gallego YA, Mendes A, Madeira LM, Nunes SP (2005) Proton electrolyte membrane properties and direct methanol fuel cell performance. J Power Sources 140 34-40... 

Peron J, Ruiz E, Jones DJ et al (2008) Solution sulfonation of a novel polybenzimidazole. A proton electrolyte for fuel cell application. J Membr Sci 314 247-256... 

Springer, X E., Zawodzinski, X A., and Gottesfeld, S. 1991. Proton electrolyte fuel cell model. /. Electro-chem. Soc. 138 2334-2341. 

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