Principles of DMFCs

A direct methanol fuel cell consists of two electrodes—a catalytic methanol anode and a catalytic oxygen cathode—separated by an ionic conduc- 

In such a device, the electrons liberated at the anode by the oxidation of methanol circulate in the external electrical circuit, producing electrical energy, and reach the cathode, where they reduce the oxidant, usually oxygen from air. The overall reaction thus corresponds to the catalytic combustion of methanol with oxygen, i.e., 

The electrochemical oxidation of methanol occurs on the anode electrocatalyst (e.g., dispersed platinum), which constitutes the negative electrode of the cell  

The cell potential E is thus equal to the difference between the electrode potentials of each electrode  

One main advantage of such a power source is the direct transformation of the chemical energy of methanol combustion into electrical energy. Hence, the reversible cell potential, can be calculated from the Gibbs energy change, AG, associated with the overall combustion reaction of methanol (1), by the equation  

---

Fig. 17.2 Detailed working principle of DMFC. (Reprinted with permission from [18]. Copyright 2005 Elsevier)...

Direct methanol fuel cells are a class of polymer electrolyte membrane (PEM) fuel cells that typically employ a cation exchange membrane to separate the anode and cathode compartments. To illustrate the basic principles of DMFC operations, we shall take a typical, liquid-feed cell with a cation exchange membrane (alkaline exchange membranes are an alternative, and these are discussed later in this chapter). This is depicted in Figure 5.1. 

---