Oxygen fuel cell, reaction

Fig. 11.21. Exergy vector diagram of hydrogen-oxygen fuel cell reaction at room temperature.

H20(g) (hydrogen-oxygen fuel-cell reaction) 2 Fe203(s) (rusting of iron)... 

The electrons produce an electric current as they travel through the wire from the anode to the cathode. The hydrogen ions flow through the plastic membrane to the cathode. At the cathode, oxygen molecules are reduced to oxide ions that combine with the hydrogen ions to form water. The overall hydrogen-oxygen fuel cell reaction can be written as... 

Change of Enthalpy, Gibbs Free Energy, and Entropy of Hydrogen/Oxygen Fuel Cell Reaction (in kJmoL K" ) with Temperature and Resulting Theoretical Cell Potential... 

The quantities Vj and are the stoichiometric coefficients for the fuel cell reaction, and andare the fugacities of fuel and oxygen in their respective streams. 

A hydrogen-oxygen fuel cell operates on the reaction ... 

For the study of the electrocatalytic reduction of oxygen and oxidation of methanol, our approach to the preparation of catalysts by two-phase protocol " provides a better controllability over size, composition or surface properties in comparison with traditional approaches such as coprecipitation, deposition-precipitation, and impregnation. " The electrocatalytic activities were studied in both acidic and alkaline electrolytes. This chapter summarizes some of these recent results, which have provided us with further information for assessing gold-based alloy catalysts for fuel cell reactions. 

This reaction of water electrol3 is is the same as, but reverse in its direction to, the reaction of hydrogen-oxygen fuel cell in Eqn. 6-1. Note that the anode and the cathode are reversed in the chemical and the electrolytic cells. 

The spent oxidant composition is calculated in a similar manner. We note that in the MCFC, both oxygen and carbon dioxide are consumed on the cathode (air) side. This can be seen from the cathode reaction listed below and the following table listing the fuel cell reaction quantities. 

The catalyst layers (the cathode catalyst layer in particular) are the powerhouses of the cell. They are responsible for the electrocatalytic conversion of reactant fluxes into separate fluxes of electrons and protons (anode) and the recombination of these species with oxygen to form water (cathode). Catalyst layers include all species and all components that are relevant for fuel cell operation. They constitute the most competitive space in a PEFC. Fuel cell reactions are surface processes. A primary requirement is to provide a large, accessible surface area of the active catalyst, the so-called electrochemically active surface area (ECSA), with a minimal mass of the catalyst loaded into the structure. 

The chemical reaction that takes place in the pentane-oxygen fuel cell is C2H12 (g) + 8 O2 (g) 5 CO2 (g) + 6H2O (1)... 

A hydrogen/oxygen fuel cell, operating at near-standard conditions to produce liquid water as the reaction product, delivers 50 A at 0.70 V. What is the efficiency of the cell ... 

From the data in Appendix C, calculate the theoretical maximum EMF of a methane/oxygen fuel cell with an acidic electrolyte under standard conditions. Assume the products to be liquid water and aqueous CO2. [Hint You need to know the number of electrons transferred per mole CH4 consumed. Write a balanced equation for the net reaction, and obtain the number of electrons from Eq. 15.47.] [Answer 1.05 V.]... 

Is the reaction that goes on in a hydrogen-oxygen fuel cell an example of electrolysis ... 

Figure 19.18. Data of electrochemical fuel cells, (a) Processes in a fuel cell based on the reaction between hydrogen and oxygen, (b) Voltage-current characteristic of a hydrogen-air fuel cell operating at 125°C with phosphoric acid electrolyte [Adlharl, in Energy Technology Handbook (Considine, Ed.), 1977, p. 4.61). (c) Theoretical voltages of fuel cell reactions over a range of temperatures, (d) Major electrochemical systems for fuel cells (Adlharl, in Considine, loc. cit., 1977, p. 4.62).

One of the economic incentives for the study of reaction (44) is that the reaction relates to the successful development of methanol—oxygen and hydrogen—oxygen fuel cells which are capable of extremely efficient conversion of the energy contained in a fuel to electricity. 

Using the standard free energies of formation in Appendix B, calculate the standard cell potential for the reaction in the hydrogen-oxygen fuel cell ... 

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