Proton exchange membrane fuel cells schematic

Proton exchange membrane fuel cell schematic. 10... 

The PEMFC (Proton Exchange Membrane Fuel Cell) is a fuel cell with a protonconducting fluorinated polymer as electrolyte. Figure 14.12 gives a schematic drawing of the PEMFC. At the anode, hydrogen is oxidized to protons. At the cathode, oxygen from air is reduced to water. The PEMFC is in development for various applications. 

Figure 5 Schematics of a typical proton-exchange membrane fuel cell, indicating the platinum-based electrodes used for hydrogen oxidation and oxygen reduction, the interconnecting electrolyse, and the electrical circuit used to harvest the energy produced. (Reprinted from Ref. 35, 1998, with permission from Elsevier)...

Figure 3.33. Schematic picture of a proton exchange membrane fuel cell. Modelling of reactions at the gas diffusion layer/catalyst/membrane interfaces A and B is discussed in section 3.5.2. Details of design are discussed in the following subsections.

Figure 10.1 Schematic drawing of a proton-exchange membrane fuel cell. CL = catalyst layer GDL = gas diffusion layer.

Figure 12. Schematic dependence of output voltage and power density on electrical current density from a proton exchange membrane fuel cell. Reprinted from [44] with permission from Elsevier.

Chemical reactions are temperature sensitive, and indeed, chemical rate constants and reactions mechanism are expected to vary considerably with temperature. Most investigations on the electrocatalysis of the ORR are usually performed at ambient conditions, which do not necessarily represent the behavior of the materials and the reaction at the conditions of practical interest. For example, in proton exchange membrane fuel cells, the temperature of operation is between 80 and 100 °C. Significant discrepancy in behavior may arise if reactions and materials are tested at ambient conditions and their behavior at high temperatures is merely deduced firom extrapolation. Schafer et al. introduced variable temperature SECM, with an operational range of 0-100 °C, by integrating a temperature control unit (Peltier element) into an SECM setup, as shown in the schematic of Fig. 23 [66]. At the heart of the temperature control unit is the Peltier element, which is housed in a stainless steel block. 

Figure 18.3. A schematic showing the mechanism of particle growth by dissolution/precipitation. The chemical potential of smaller particles is higher than that of larger particles [32]. (Reproduced by permission of ECS— The Electrochemical Society, from Virkar AV, Zhou Y. Mechanism of catalyst degradation in proton exchange membrane fuel cells.)...

Figure 18.5. Schematic representing platinum surface area loss on the nanometer seale, where platinum particles grow on carhon support via Ostwald ripening, and on the micrometer scale, where dissolved platinum species difliise toward the membrane [31]. (Reproduced by permission of ECS—The Electrochemical Society, from Ferreira PJ, la O GJ, Shao-Hom Y, Morgan D, Makharia R, Kocha S, et al. histahility of Pt/C electrocatalysts in proton exchange membrane fuel cells.)...

FIGURE 43.2 Schematic representation of proton-exchange membrane fuel cell stack. 

Proton exchange membrane fuel cell (PEMFC), schematically shown in Figure 3.7, is using a polymeric proton exchange membrane (PEM) as an electrolyte at temperatures from ambient up to around 120°C. Nafion is used for PEM and Pt for electrodes. Both of these materials are very expensive. The durability of the PEMFC is still under studies for a wide implementation. This fuel cell is considered a first candidate for automotive applications. 

Figure 2.1 shows a schematic structure of the fuel cell membrane electrode assembly (MEA), including both anode and cathode sides. Each side includes a catalyst layer and a gas diffusion layer. Between the two sides is a proton exchange membrane (PEM) conducting protons from the anode to the cathode. 

Figure 4.1 shows a schematic of a typical polymer electrolyte membrane fuel cell (PEMFC). A typical membrane electrode assembly (MEA) consists of a proton exchange membrane that is in contact with a cathode catalyst layer (CL) on one side and an anode CL on the other side they are sandwiched together between two diffusion layers (DLs). These layers are usually treated (coated) with a hydrophobic agent such as polytetrafluoroethylene (PTFE) in order to improve the water removal within the DL and the fuel cell. It is also common to have a catalyst-backing layer or microporous layer (MPL) between the CL and DL. Usually, bipolar plates with flow field (FF) channels are located on each side of the MFA in order to transport reactants to the... 

Schematic diagram of the experimental set-up for a PEM (proton exchange membrane or polymer electrolyte membrane) hydrogen fuel cell...

Direct Alcohol Fuel Cells (DAFCs), Fig. 1 Schematic diagram of a DEFC based on a proton exchange membrane... 

Fig. 2.1 A schematic presentation of (a) a proton-exchange membrane (PEMFC) and (b) an alkaline membrane fuel cell (AMFC), both fuelled either with H2 gas or directly with methanol (DMFC mode). The stoichiometric ratios of reactants and products are shown in each case...

At the heart of a PEM fuel cell is a polymer membrane that has some unique capabilities. It is impermeable to gases but it conducts protons (hence the name, proton exchange membrane). The membrane that acts as the electrol5q e is squeezed between the two porous, electrically conductive electrodes. These electrodes are typically made out of carbon doth or carbon fiber paper. At the interface between the porous electrode and the polymer membrane there is a layer with catalyst particles, typically platinum supported on carbon [1]. A schematic diagram of cell configuration and basic operating principles is shown in the Figure in.l. 

Girishkumar and co-workers [190] reported a preparation procedure for the MEA using CNTs as a support for PEM fuel cells. A schematic representation of their CNT-based proton exchange membrane assembly for a H2/O2 based fuel cell is shown in Figure 14.25. In their experiment, an electrophoretic deposition technique was employed to cast films of CNTs on carbon fiber paper. Two carbon paper electrodes are kept 5 mm apart in a cell containing a CNT suspension in... 

Figure 2.1 Schematic of a proton-exchange membrane (PEM) fuel cell 8...

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