Alkaline direct alcohol fuel cells anode catalysts

Anode Catalysts for Alkaline Direct Alcohol Fuel Cells and Characteristics of the Catalyst Layer... 

In this work an overview of anode catalysts for alkaline direct alcohol fuel cells, and reports of the testing of these materials in alkaline direct alcohol fuel cells fuelled with Ci (methanol) and C2 (ethanol and ethylene glycol) alcohols, is presented. 

Chen YG, Zhuang L, Lu JT (2007) Non-Pt anode catalysts for alkaline direct alcohol fuel cells. Chinese J Catal 28(10) 870-874... 

DMFCs and direct ethanol fuel cells (DEFCs) are based on the proton exchange membrane fuel cell (PEM FC), where hydrogen is replaced by the alcohol, so that both the principles of the PEMFC and the direct alcohol fuel cell (DAFC), in which the alcohol reacts directly at the fuel cell anode without any reforming process, will be discussed in this chapter. Then, because of the low operating temperatures of these fuel cells working in an acidic environment (due to the protonic membrane), the activation of the alcohol oxidation by convenient catalysts (usually containing platinum) is still a severe problem, which will be discussed in the context of electrocatalysis. One way to overcome this problem is to use an alkaline membrane (conducting, e.g., by the hydroxyl anion, OH ), in which medium the kinetics of the electrochemical reactions involved are faster than in an acidic medium, and then to develop the solid alkaline membrane fuel cell (SAMFC). 

As membrane material for their direct ammonia-oxygen fuel cells, Lan and Tao used a blend of the anion-exchange resin Amberlite IRA 400 (hydroxide form) and poly(vinyl alcohol). As cathode material, Mn02 deposited on carbon materials was used. In different cell versions the anodes were prepared from Pt-Ru-C and from chrom-decorated nanosized nickel (size about 6 nm). Experiments with such cells at room temperature showed maximal power densities in the range 12 to 16 mW/cm. In some cases the power densities for ammonia-fed cells were higher than those for hydrogen-fed cells. The authors note that the development of direct ammonia fuel cells with alkaline membranes and inexpensive catalysts is still at an early stage. 

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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