The development of the alkaline anion exchange membrane (AEM) for the direct liquid fuel cell opened up opportunities for the use of new fuels (that oxidized inefficiently in PEM fuel cells) and new catalysts (that corroded easily in PEM fuel cells). The first fuel studied in depth was ethanol because it oxidizes much more efficiently in alkaline media than acidic media. Since then, several other fuels have been studied including formate, propanol, ethylene glycol (EG), propylene glycol (PG), and glycerol (G). One commonality with these fuels is that they all oxidize efficiently on palladium catalysts. However, formate is the most efficient of these fuels, and significant improvements in the efficiency of all these fuels are needed for implementation.<br/>The CNT support provided a significant advantage over standard, activated carbon support in several of the fuels. The increase in oxidation rate in formate, for example, was 5-fold. However, the oxidation rate of propanol was not significantly enhanced by the CNT support.<br/>We are presently exploring the scientific reason for the enhanced oxidation rates by the CNT support. Masel, et al, suggested that the CNT provides enhancement due to its electronic properties, and a shift in Pd 3d (5/2) binding energy supports this. However, we are presently investigating why the promotion in alkaline media is so much greater than in acidic media, even for the formate (compared with formic acid).

Pd/CNT catalysts for electrochemical oxidation of small organic molecules in alkaline media

251st National Meeting (2016)

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