Nanocomposite PEMs

SPEEK-inorganic (Si02, zirconium phosphate, and sulfenylphosphonate) nanocomposite PEMs are prepared either by infiltration of ZrOQ2, followed by reaction with phosphoric acid, or by blending of mesoporous ZrP/Si02 [60-64]. 

Keywords Hybrid ionomeric membrane Inorganic particles and networks Nanocomposite membrane PEM fuel cell membrane... 

In PEM fuel cells (PEMFCs), the function of catalyst support layer is to accommodate the catalyst nanoparticles. Nanocomposite such as PEDOT/ carbon nanofiber has proved to be an efficient catalyst support in PEMFCs [40]. 

Proton exchange membranes The proton exchange membrane (PEM) is one of the major components in solid-type fuel cells, such as in PEM and direct methanol fuel cells. Up to now many research groups have reported the fabrication of polymer/silica nanocomposites as a PEM. 

Table 10.3. Average crystallite size of Pt nanoparticles, electrochemically active area (EAA), peak current density, and mass activity for the methanol oxidation reaction of various Pt/MWCNT nanocomposite catalysts. The average size of Pt nanoparticles was obtained by XRD analysis [84]. (Reproduced from Journal of Power Sources, 161(2), Travitsky N, Ripenbein T, Golodnitsky D, Rosenberg Y, Burshtein L, Peled E. Pt-, PtNi-and PtCo-supported catalysts for oxygen reduction in PEM fuel cells, 782-9, 2006, with permission from Elsevier.)...

Reaction rates are lower in fuel cells than in other batteries, so an electrocatalyst is used to decrease the activation energy (Section 16.7). The PEM cell s electrodes are made of a nanocomposite consisting of a Pt-based catalyst deposited on graphite. These are embedded in a polymer electrolyte membrane having a perfluoroethylene backbone (HEjC—CFj] ) with attached sulfonic acid gronps (RSO3") that play a key role in ferrying protons from anode to cathode. 

Ghosh S, Maity S, Jana T (2011) Polybenzimidazole/ silica nanocomposites organic-inorganic hybrid membranes for PEM fnel cell. J Mater Chem 21 14897-14906... 

The investigations of Carbon films in Metal/Carbon Nanocomposites and their peculiarities are carried out by Raman spectroscopy with the using of Laser Spectrometer Horiba LabRam HR 800. Below the Raman spectra and PEM microphotograph of Copper/Carbon (Cu/C) Nanocomposite are represented (Figs. 1.6 and 1.7). 

Fig. 7.3 Conductivity dependence on the activity of water vapor for nanocomposite Nafion-M02 (M = Zr, Si, Ti) and Nafion membrane at 120°C. Reprinted with permission from Ref. [33] N. H. Jalani, et al., Synthesis and characterization of Nafion -M02 (M = Zr, Si, Ti) nanocomposite membranes for higher temperature PEM fuel cells, Electrochim. Acta 51, 553-560 (2005). Copyright Elsevier...

Seger, B. and Kamat P.V. (2009) Electrocalalytically active graphene platinum nanocomposites role of 2-D carbon support in PEM foel cells. The Journal of Physical Chemistry C, 113 (19), 7990 7995. 

The structure and the surface morphology of the nanocomposite samples were studied using the atomic force microscopy (Solver P-47) and transmission electron microscopy (PEM-100) techniques. Analysis showed that the samples contained the uniformly distributed nanopartides of used materials with sizes of 10-25 nm. Figure 7.2 presents the typical transmission electron microscope image of a nanocomposite sample containing 5% nanopartides MnO. As can be seen, MnO particles are situated on the sample surface. These particles are distributed quite uniformly and have dimensions of about 10 nm, but not exceeding 20 nm. 

Polyaniline (PANI) nanocomposite membranes are also prepared by a sol-gel process, embedding silica in the hydrophilic clusters (Nafion) followed by its deposition by redox polymerization [51]. PANI modified the membrane structure and reduced the methanol crossover, while silica Incorporation improved the conductivity and stability. Zeolite has been incorporated as potential filler for PEMs, either by blending or by infiltration in swelled membrane, to reduce the methanol permeability and enhance the thermal stabihty [52,53]. Although the fuel cell performance of these membranes was Inferior compared with pristine Nafion membrane, incorporation of semipermeable particles is an effective method to engineer the transport properties of composite membranes. Chen et al [54] reported nanocomposite membranes by in situ hydrothermal crystallization method, with similar proton conductivity, but low methanol permeability (40% less) in comparison with Nafion membrane. These membranes showed higher OCV (3%) and power density (21%) than Nafion. 

Sidfonated hydrocarbon polymers are widely used as a host matrix to prepare organic-inorganic nanocomposite for high-temperature PEM applications due to their excellent stability and high susceptibility to electrophilic sulfonation reactions for acid fimctionalization. Sulfonation of thermally resistant polymers such as polysulfones (PSF), fluoropolymers, and polyetheretherketone (PEEK) was widely studied. The sulfonation of certain polymers such as polystyrenes... 

Jalani NH, Duim K, Datta R (2005) Synthesis and characterization of Nafion -M02 (M = Zr, Si, Ti) nanocomposite membranes for higher temperature PEM fuel cells. Electrochim Acta 51(3) 553-560... 

Importantly, for elevated temperature PEM fuel cell operation, the HPAs may be structurally stable to >600°C, although under anhydrous conditions their stability may be limited to 200°C, and they incorporate some water molecules and protons up to >300°C depending on the system [15]. Because of their structural diversity, these materials are particularly suitable for incorporation into a wide variety of membrane materials for which they can be specifically tailored. They have been studied in four composite systems HPAs infused into perfluorinated sulfonic acid (PFSA) polymers such as Nafion [16,17], HPA cast in inert matrices such as poly (vinyl alcohol) (PVA) [18], HPA immobilized in polymer/silicate nanocomposites via sol-gel methods [19], and HPA directly incorporated into polymer films via functionalization to monomers [20]. Here after a discussion of fundamental studies, we review the various HPA-based materials used for fuel cells. 

Tripathi, B.P., Kumar, M., Shahi, V.K., Highly stable proton conducting nanocomposite polymer electrolyte membrane (PEM) prepared by pore modifications An extremely low methanol permeable PEM, J. Membr. Sci., 2009, 327, 145-154. 

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