Direct methanol fuel cell cathode catalyst current density

Many research groups have reported the fuel cell performance of Pt nanoparticles supported on CNTs at the cathode of H2/O2 fuel cells or direct methanol fuel cells [63, 65, 66, 68, 69, 71, 81, 87, 188, 189, 191-193]. It has been shown that the performance of a CNT-based MEA is better than that of conventional Pt/C MEA [65, 71, 81, 189, 191-193]. For example, Matsumoto and coworkers [193] conducted the fuel cell tests of the MEA with CNTs used as a support for Pt catalysts at the cathode. The authors concluded that enhancements in PEM fuel cell performance are observed by using the CNT cathode in comparison to a conventional carbon cathode in a low current density region (Figure 14.27). The voltage drop above 400 mA/cm was ascribed to the proton diffusion. 

HjSO, but the magnitude of the current density was not affected largely up to a concentration of lOmmol dm . With 2-propanol, the current due to the alcohol oxidation was superimposed on the ORR current, and the potential shifted by approximately 0.5 V at 0.1 mol dm . Both 2-propanol and acetone are MEA components because 2-propanol is added to the catalyst ink, and acetone is produced by oxidation of 2-propanol on the platinum cathode. The effects are, however, not serious because their concentration is less than lOmmol dm . Methanol is used as a fuel in direct methanol fuel cells, and crossover through the polymer electrolyte membrane is known to cause a degradation of the ORR at the cathode, when the concentration of the fuel is as high as 5 mol dm . 

Fig. 21 Current density-cell voltage and power density characteristic for different concentration of Mn02 catalyst at cathode in 2 M methanol/3 M KOH solution in direct alcohol alkaline fuel cell at 25°C, Anode Pt-black.

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